NumPy: Array Object Exercises, Practice, Solution

(2, 3)
int32

Click me to see the sample solution

38. Reshape Array (Keep Data)

Write a NumPy program to create another shape from an array without changing its data.

Reshape 3x2:

[[1 2]
[3 4]
[5 6]]

Reshape 2x3:
[[1 2 3]
[4 5 6]]

Click me to see the sample solution

39. Change Array Data Type

Write a NumPy program to change an array's data type.

Expected Output:

[[ 2 4 6]
[ 6 8 10]]

Data type of the array x is: int32

New Type: float64
[[ 2. 4. 6.]
[ 6. 8. 10.]]

Click me to see the sample solution

40. 3x5 Array Filled with 2s

Write a NumPy program to create a new array of 3*5, filled with 2.

Expected Output:

[[2 2 2 2 2]
[2 2 2 2 2]
[2 2 2 2 2]]
[[2 2 2 2 2]
[2 2 2 2 2]
[2 2 2 2 2]]

Click me to see the sample solution

41. Array of 10s with Given Shape

Write a NumPy program to create an array of 10's with the same shape and type as the given array.

Sample array: x = np.arange(4, dtype=np.int64)

Expected Output:
[10 10 10 10]

Click me to see the sample solution

42. 3D Array with Diagonal Ones

Write a NumPy program to create a 3-D array with ones on a diagonal and zeros elsewhere.

Expected Output:

[[ 1. 0. 0.]
[ 0. 1. 0.]
[ 0. 0. 1.]]

Click me to see the sample solution

43. 2D Array with Custom Diagonal Values

Write a NumPy program to create a 2-D array whose diagonal equals [4, 5, 6, 8] and 0's elsewhere.

Expected Output:

[[4 0 0 0]
[0 5 0 0]
[0 0 6 0]
[0 0 0 8]]

Click me to see the sample solution

44. 1D Array (0?50) & (10?50)

Write a NumPy program to create a 1-D array with values from 0 to 50 and an array from 10 to 50.

Expected Output:

Array from 0 to 50:

[ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49]

Array from 10 to 50:
[10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
35 36 37 38 39 40 41 42 43 44 45 46 47 48 49]

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45. 30 Evenly Spaced Values (2.5?6.5)

Write a NumPy program to create a 1-D array of 30 evenly spaced elements between 2.5 and 6.5, inclusive.

Expected Output:

[ 2.5 2.63793103 2.77586207 2.9137931 3.05172414 3.18965517
.................
5.81034483 5.94827586 6.0862069 6.22413793 6.36206897 6.5 ]

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46. 20 Log-Spaced Values (2?5)

Write a NumPy program to create a 1-D array of 20 elements spaced evenly on a log scale between 2. and 5., exclusive.

Expected Output:

[ 100. 141.25375446 199.5262315 281.83829313
......................
25118.8643151 35481.33892336 50118.72336273 70794.57843841]

Click me to see the sample solution

47. Create Zero/One Array Template

Write a NumPy program to create an array like the one below.

Expected Output:

[[ 0. 0. 0.]
...........
[ 1. 1. 1.]]

Click me to see the sample solution

48. Create 2D Array with Specific Values

Write a NumPy program to create an array like the one below.

Expected Output:

[[ 2 3 4]
[ 5 6 7]
[ 0 9 10]
[ 0 0 13]]

Click me to see the sample solution

49. Collapse 3D Array to 1D

Write a NumPy program to collapse a 3-D array into a one-dimensional array.

Expected Output:

3-D array:
[[ 1. 0. 0.]
[ 0. 1. 0.]
[ 0. 0. 1.]]

One dimension array:
[ 1. 0. 0. 0. 1. 0. 0. 0. 1.]

Click me to see the sample solution

50. Find 4th Element of Array

Write a NumPy program to find the 4th element of a specified array.

Expected Output:

[[ 2 4 6]
[ 6 8 10]]

Forth e1ement of the array:
6

Click me to see the sample solution

51. Change Two Array Axes

Write a NumPy program to change two array axes.

Sample array: [[1 2 3]]

Expected Output:
[[1]
[2]
[3]]

Click me to see the sample solution

52. Move Array Axes to Alternate Positions

Write a NumPy program to move array axes to alternate positions. Other axes remain in their original order.

Expected Output:

(3, 4, 2)
(4, 2, 3)

Click me to see the sample solution

53. Move Axis to Desired Position

Write a NumPy program to move the specified axis backwards, until it lies in a given position.

Move the following 3rd array axes to first position.
(2,3,4,5)

Sample Expected Output:
(2, 5, 3, 4)

Click me to see the sample solution

54. Inputs as Arrays with 1+ Dimensions

Write a NumPy program to convert specified inputs into arrays with at least one dimension.

Expected Output:

[ 12.]
[[ 0. 1. 2.]
[ 3. 4. 5.]]

[array([1]), array([3, 4])]

Click me to see the sample solution

55. Inputs as Arrays with 2D/3D Views

Write a NumPy program to view inputs as arrays with at least two dimensions, three dimensions.

Expected Output:

View inputs as arrays with at least two dimensions:
[10]
[[ 0. 1.]
[ 2. 3.]]

View inputs as arrays with at least three dimensions:
[[[15]]]
[[[ 0.]
[ 1.]
[ 2.]]]

Click me to see the sample solution

56. Insert New Axis in 2D Array

Write a NumPy program to insert a new axis within a 2-D array.

2-D array of shape (3, 4).

Expected Output:

New shape will be will be (3, 1, 4).

Click me to see the sample solution

57. Remove Single-Dimensional Entries

Write a NumPy program to remove single-dimensional entries from a specified shape.

Specified shape: (3, 1, 4)

Expected Output: (3, 4)

Click me to see the sample solution

58. Concatenate 2D Arrays

Write a NumPy program to concatenate two 2-dimensional arrays.

Expected Output:

Sample arrays: ([[0, 1, 3], [5, 7, 9]], [[0, 2, 4], [6, 8, 10]]

Expected Output:
[[ 0 1 3 0 2 4]
[ 5 7 9 6 8 10]]

Click me to see the sample solution

59. Convert 1D Arrays to 2D (as Columns)

Write a NumPy program to convert 1-D arrays as columns into a 2-D array.

Sample array: (10,20,30), (40,50,60)

Expected Output:

[[10 40]
[20 50]
[30 60]]

Click me to see the sample solution

Write a NumPy program to convert (in sequence depth wise (along the third axis)) two 1-D arrays into a 2-D array.

Sample array: (10,20,30), (40,50,60)

Expected Output:

[[[10 40]]
[[20 50]]
[[30 60]]]

Click me to see the sample solution

61. Split 14 Elements into 3 Arrays

Write a NumPy program to split an array of 14 elements into 3 arrays, each with 2, 4, and 8 elements in the original order.

Expected Output:

Original array: [ 1 2 3 4 5 6 7 8 9 10 11 12 13 14]

After splitting:
[array([1, 2]), array([3, 4, 5, 6]), array([ 7, 8, 9, 10, 11, 12, 13, 14])]

Click me to see the sample solution

62. Split 4x4 Array Along Second Axis

Write  a NumPy program that splits an array of shape 4x4 into two arrays along the second axis.

Sample array :
[[ 0 1 2 3]
........
[12 13 14 15]]

Expected Output:
[array([[ 0, 1],
[ 4, 5],
[ 8, 9],
[12, 13]]),

array([[ 2, 3],
[ 6, 7],
[10, 11],
[14, 15]]), array([], shape=(4, 0), dtype=int64)]

Click me to see the sample solution

63. Count Non-Zero Elements in Array

Write a NumPy program to get the number of non-zero elements in an array.

Expected Output:

Original array:
[[ 0 10 20]
[20 30 40]]

Number of non zero elements in the above array:
5

Click me to see the sample solution

64. 5x5 Matrix with Row Values 0?4

Write a NumPy program to create a 5x5 matrix with row values ranging from 0 to 4.

Original array:
[[ 0. 0. 0. 0. 0.]
.........
[ 0. 0. 0. 0. 0.]]

Row values ranging from 0 to 4.
[[ 0. 1. 2. 3. 4.]
..........
[ 0. 1. 2. 3. 4.]]

Click me to see the sample solution

65. Check Values Present in Array

Write a NumPy program to test whether specified values are present in an array.

Expected Output:

Original array:
[[ 1.12 2. 3.45]
[ 2.33 5.12 6. ]]

True
False
True
False
True

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66. Vector of Size 10 (0?1 Excluded)

Write a NumPy program to create a vector of size 10 with values ranging from 0 to 1, both excluded.

Expected Output:

[ 0.09090909 0.18181818 0.27272727 0.36363636 0.45454545 0.54545455
0.63636364 0.72727273 0.81818182 0.90909091]

Click me to see the sample solution

67. Make Array Read-Only

Write a NumPy program to make an array immutable (read-only).

Expected Output:

Test the array is read-only or not:
Try to change the value of the first element:
Traceback (most recent call last):

File "19236bd0-0bd9-11e7-a232-c706d0968eb6.py", line 6, in
x[0] = 1

ValueError: assignment destination is read-only

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68. Sum Multiples of 3 or 5 Below 100

Write a NumPy program (using numpy) to sum all the multiples of 3 or 5 below 100.

Expected Output:
[ 3 5 6 9 10 12 15 18 20 21 24 25 27 30 33 35 36 39 40 42 45 48 50 51 54
55 57 60 63 65 66 69 70 72 75 78 80 81 84 85 87 90 93 95 96 99]
2318

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69. Create Array with 10^3 Elements

Write a NumPy program to create an array with 10^3 elements.

Expected Output:

[ 0. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23.
24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35.
- - - - - - - - - - - - - - - - -
972. 973. 974. 975. 976. 977. 978. 979. 980. 981. 982. 983.
984. 985. 986. 987. 988. 989. 990. 991. 992. 993. 994. 995.
996. 997. 998. 999.]

Click me to see the sample solution

70. Display Every Array Element

Write a NumPy program to create and display every element of a NumPy array.

Expected Output:

0 1 2 3 4 5 6 7 8 9 10 11

Click me to see the sample solution

71. Display Array Elements in Fortran Order

Write a NumPy program to create and display every element of a NumPy array in Fortran order.

Expected Output:

Elements of the array in Fortan array:

0 4 8 1 5 9 2 6 10 3 7 11

Click me to see the sample solution

72. Create 5x5x5 Cube of 1?s

Write a NumPy program to create a 5x5x5 cube of 1's.

Expected Output:

[[[1 1 1 1 1]
[1 1 1 1 1]
[1 1 1 1 1]
[1 1 1 1 1]
[1 1 1 1 1]]
............
[[1 1 1 1 1]
[1 1 1 1 1]
[1 1 1 1 1]
[1 1 1 1 1]
[1 1 1 1 1]]]

Click me to see the sample solution

73. Multiply Array (3,4) Elements by 3

Write a NumPy program to create an array of (3, 4) shapes, multiply every element value by 3 and display the result array.

Expected Output:

Original array elements:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]]

New array elements:
[[ 0 3 6 9]
[12 15 18 21]
[24 27 30 33]]

Click me to see the sample solution

74. Combine 1D and 2D Arrays

Write a NumPy program to combine a one and two dimensional array together and display their elements.

Expected Output:

One dimensional array:
[0 1 2 3]

Two dimensional array:
[[0 1 2 3]
[4 5 6 7]]
0:0
1:1
2:2
3:3
0:4
1:5
2:6
3:7

Click me to see the sample solution

75. Zeros Array with Multiple Column Types

Write a NumPy program to create an array of zeros and three column types (integer, floating, and character).

Expected Output:

[(1, 2., b'Albert Einstein') (2, 2., b'Edmond Halley')
(3, 3., b'Gertrude B. Elion')]

Click me to see the sample solution

76. Apply Cube Function to All Elements

Write a NumPy program to create a function cube for all array elements.

Expected Output:

[ 1 8 27]

Click me to see the sample solution

77. Chunkify (3,4) Array Elements

Write a NumPy program to create an array of (3, 4) shapes and convert the array elements into smaller chunks.

Expected Output:

Original array elements:

[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]]
[0 4 8]
[1 5 9]
[ 2 6 10]
[ 3 7 11]

Click me to see the sample solution

78. Create Record Array from Flat Lists

Write a NumPy program to create a record array from a (flat) list of arrays.

Sample arrays: [1,2,3,4], ['Red', 'Green', 'White', 'Orange'], [12.20,15,20,40]

Expected Output:

(1, 'Red', 12.2)
(2, 'Green', 15.0)
(3, 'White', 20.0)

Click me to see the sample solution

79. Generate 2D Gaussian-Like Array

Write a NumPy program to generate a generic 2D Gaussian-like array.

Expected Output:

2D Gaussian-like array:
[[ 0.36787944 0.44822088 0.51979489 0.57375342 0.60279818 0.60279818
0.57375342 0.51979489 0.44822088 0.36787944]
..........
[ 0.36787944 0.44822088 0.51979489 0.57375342 0.60279818 0.60279818
0.57375342 0.51979489 0.44822088 0.36787944]]

Click me to see the sample solution

80. Convert NumPy Array to Python List

Write a NumPy program to convert a NumPy array into a Python list structure.

Expected Output:

Original array elements:
[[0 1]
[2 3]
[4 5]]

Array to list:
[[0, 1], [2, 3], [4, 5]]

Click me to see the sample solution

81. Access Array by Column

Write a NumPy program to access an array by column.

Expected Output:

Original array elements:
[[0 1]
[2 3]
[4 5]]

Access an array by column:

First column:
[0 1]

Second column:
[2 3]

Third column:
[4 5]

Click me to see the sample solution

Write a NumPy program to convert a NumPy array of floating values to a numpy array of integer values.

Expected Output:

Original array elements:
[[ 12. 12.51]
[ 2.34 7.98]
[ 25.23 36.5 ]]

Convert float values to intger values:
[[12 12]
[ 2 7]
[25 36]]

Click me to see the sample solution

83. Display Float Array with Precision

Write a NumPy program to display a NumPy array of floating values with precision.

Expected Output:

Original array elements:
[ 0.26153123 0.52760141 0.5718299 0.5927067 0.7831874 0.69746349
0.35399976 0.99469633 0.0694458 0.54711478]

Print array values with precision 3:
[ 0.262 0.528 0.572 0.593 0.783 0.697 0.354 0.995 0.069 0.547]

Click me to see the sample solution

84. Suppress Scientific Notation in Array

Write a NumPy program to suppress the use of scientific notation for small numbers in a NumPy array.

Expected Output:

Original array elements:

[ 1.60000000e-10 1.60000000e+00 1.20000000e+03 2.35000000e-01]

Print array values with precision 3:

[ 0. 1.6 1200. 0.235]

Click me to see the sample solution

85. Generate 10 Integers from Generator

Write a NumPy program to create a NumPy array of 10 integers from a generator.

Expected Output:
[0 1 2 3 4 5 6 7 8 9]

Click me to see the sample solution

86. Add Extra Column to Array

Write a NumPy program to add an extra column to a NumPy array.

Expected Output:

[[ 10 20 30 100]
[ 40 50 60 200]]

Click me to see the sample solution

87. Find Distinct Rows in Array

Write a NumPy program to find distinct rows in a NumPy array.

Expected Output:

Original array:

[[20 20 20 0]
.......
[10 20 20 20]]
Unique rows of the above array:

[[ 0 20 20 20]
[10 20 20 20]
[20 20 20 0]]

Click me to see the sample solution

88. Replace Array Elements > Specified

Write a NumPy program to replace all elements of NumPy array that are greater than the specified array.

Expected Output:

Original array:

[[ 0.42436315 0.48558583 0.32924763]
[ 0.7439979 0.58220701 0.38213418]
[ 0.5097581 0.34528799 0.1563123 ]]

Replace all elements of the said array with .5 which are greater than. 5

[[ 0.42436315 0.48558583 0.32924763]
[ 0.5 0.5 0.38213418]
[ 0.5 0.34528799 0.1563123 ]]

Click me to see the sample solution

89. Remove Specific Elements in Array

Write a NumPy program to remove specific elements from a NumPy array.

Expected Output:

Original array:
[ 10 20 30 40 50 60 70 80 90 100]

Delete first, fourth and fifth elements:
[ 20 30 60 70 80 90 100]

Click me to see the sample solution

90. Replace Negative Values with 0

Write a NumPy program to replace the negative values in a NumPy array with 0.

Expected Output:

Original array:
[-1 -4 0 2 3 4 5 -6]

Replace the negative values of the said array with 0:
[0 0 0 2 3 4 5 0]

Click me to see the sample solution

91. Remove Rows with Non-Numeric Values

Write a NumPy program to remove all rows in a NumPy array that contain non-numeric values.

Expected Output:

Original array:

[[ 1. 2. 3.]
[ 4. 5. nan]
[ 7. 8. 9.]
[ 1. 0. 1.]]

Remove all non-numeric elements of the said array

[[ 1. 2. 3.]
[ 7. 8. 9.]
[ 1. 0. 1.]]

Click me to see the sample solution

92. Select Indices Satisfying Conditions

Write a NumPy program to select indices satisfying multiple conditions in a NumPy array.

Sample array :

a = np.array([97, 101, 105, 111, 117])
b = np.array(['a','e','i','o','u'])

Note: Select the elements from the second array corresponding to elements in the first array that are greater than 100 and less than 110

Expected Output:

Original arrays
[ 97 101 105 111 117]
['a' 'e' 'i' 'o' 'u']

Elements from the second array corresponding to elements in the first
array that are greater than 100 and less than 110:

['e' 'i']

Click me to see the sample solution

93. Find Magnitude of Vector

Write a NumPy program to get the magnitude of a vector in NumPy.

Expected Output:

Original array:
[1 2 3 4 5]

Magnitude of the vector:
7.4161984871

Click me to see the sample solution

94. Frequency of Distinct Values in Array

Write a NumPy program to count the frequency of distinct values in a NumPy array.

Expected Output:

Original array:
[10 10 20 10 20 20 20 30 30 50 40 40]

Frequency of unique values of the said array:
[[10 20 30 40 50]
[ 3 4 2 2 1]]

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95. Check if Array is Empty

Write a NumPy program to check whether the NumPy array is empty or not.

Expected Output:
2
0

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96. Divide Each Row by Vector

Write a NumPy program to divide each row by a vector element.

Expected Output:

Original array:
[[20 20 20]
[30 30 30]
[40 40 40]]

Vector:
[20 30 40]
[[ 1. 1. 1.]
[ 1. 1. 1.]
[ 1. 1. 1.]]

Click me to see the sample solution

97. Print All Array Values

Write a NumPy program to print all array values.

Expected Output:

[[ 0. 0. 0. 0.]
[ 0. 0. 0. 0.]
[ 0. 0. 0. 0.]
[ 0. 0. 0. 0.]]

Click me to see the sample solution

98. Raw Array to Binary String/Back

Write a NumPy program to convert raw array data to a binary string and create an array.

Expected Output:

Original array:

[ 10. 20. 30.]

Binary string array:
b'\x00\x00\x00\x00\x00\x00$@\x00\x00\x00\x00\x00\x004@\x00\x00\x00\x00\x00\x00>@'

Array using fromstring():
[ 10. 20. 30.]

Click me to see the sample solution

99. Sum/Product of Array Elements

Write a NumPy program to sum and compute the product of a numpy array of elements.

Expected Output:

Original array:

[ 10. 20. 30.]

Sum of the array elements:

60.0

Product of the array elements:

6000.0

Click me to see the sample solution

100. Use put to Place Values in Array

Write a NumPy program to take values from a source array and put them at specified indices of another array.

Expected Output:

[ 10. 10. 20. 30. 30.]

Put 0 and 40 in first and fifth position of the above array

Array x after put two values: [ 0. 10. 20. 30. 40.]

Click me to see the sample solution

101. Print Full Array Without Truncation

Write a NumPy program to print the full NumPy array, without truncation.

Truncated output:

[ 0 1 2 ... 1997 1998 1999]

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102. Convert NumPy Array to CSV File

Write a NumPy program to convert a NumPy array into a CSV file.

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103. Calculate Euclidean Distance

Write a NumPy program to calculate the Euclidean distance.

From Wikipedia:

In mathematics, the Euclidean distance or Euclidean metric is the "ordinary" straight-line distance between two points in Euclidean space. With this distance, Euclidean space becomes a metric space. The associated norm is called the Euclidean norm. Older literature refers to the metric as the Pythagorean metric.

Sample Output:
Euclidean distance: 5.196152422706632

Click me to see the sample solution

104. Access Last Two Columns of 2D Array

Write a NumPy program to access the last two columns of a multidimensional column.

Sample Output:

[[1 2 3]
[4 5 6]
[7 8 9]]
[[2 3]
[5 6]
[8 9]]

Click me to see the sample solution

105. Read CSV and Store in Array

Write a NumPy program to read a CSV data file and store records in an array.

Sample CSV file: fdata.csv

Date,Open,High,Low,Close
03-10-16,774.25,776.065002,769.5,772.559998
.................
07-10-16,779.659973,779.659973,770.75,775.080017

Sample Output:
[(b'Date', nan, nan, nan, nan)
(b'03-10-16', 774.25, 776.065, 769.5 , 772.56)
......................
(b'07-10-16', 779.66, 779.66 , 770.75, 775.08)]

Click me to see the sample solution

106. Count Occurrences of Item in Array

Write a NumPy program to count the occurrences of a specified item in a given NumPy array.

Sample Output:

Original array:
[10 20 20 20 20 0 20 30 30 30 0 0 20 20 0]

1
7
3
4

Click me to see the sample solution

107. Calculate Percentiles of Array

Write a NumPy program to calculate percentiles for a sequence or single-dimensional NumPy array.

Sample Output:

50th percentile (median):
3.0

40th percentile:
2.6

90th percentile:
4.6

Click me to see the sample solution

108. Convert PIL Image to NumPy Array

Write a NumPy program to convert a PIL image into a NumPy array.

Sample Output:

[[[255 255 255 0]
.......
[255 255 255 0]]]

Click me to see the sample solution

109. Convert NumPy Array to Image

Write a NumPy program to convert a NumPy array to an image. Display an image.

Sample Output:

Click me to see the sample solution

110. Remove nan Values from Array

Write a NumPy program to remove nan values from a given array.

Sample Output:

Original array:

[200. 300. nan nan nan 700.]

After removing nan values:
[200. 300. 700.]

Original array:
[[ 1. 2. 3.]
[nan 0. nan]
[ 6. 7. nan]]

After removing nan values:
[1. 2. 3. 0. 6. 7.]

Click me to see the sample solution

111. Create Cartesian Product of Two Arrays

Write a NumPy program to create a Cartesian product of two arrays into a single array of 2D points.

Sample Output:
[[1 4]
......
[3 5]]

Click me to see the sample solution

112. Calculate Memory Usage of Array

Write a NumPy program to get NumPy array memory usage.

Sample Output:
8256

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113. Build Array of All Combinations of Three Arrays

Write a NumPy program to build an array of all combinations of three NumPy arrays.

Sample Output:

Original arrays:

Array-1
[1, 2, 3]

Array-2
[4, 5]

Array-3
[6, 7]

Combine array:
[[1 4 6]
........
[3 4 7]
[3 5 7]]

Click me to see the sample solution

114. Generate Random Rows from 2D Array

Write a NumPy program to create a random set of rows from a 2D array.

Sample Output:

Random set of rows from 2D array array:
[[4 0 2]
.......
[3 4 3]]

Click me to see the sample solution

115. Find Indices of Elements Equal to Zero

Write a NumPy program to find the indices of elements equal to zero in a NumPy array.

Sample Output:

Original array:

[1 0 2 0 3 0 4 5 6 7 8]

Indices of elements equal to zero of the said array:

[1 3 5]

Click me to see the sample solution

116. Compute Histogram of Data

Write a NumPy program to compute the histogram of a set of data.

Sample Output:

Click me to see the sample solution

117. Generate Line Graph of Data

Write a NumPy program to compute the line graph of a set of data.

Sample Output:

Click me to see the sample solution

118. Find Index of Higher Ranked Value in Array

Write a NumPy program to find the position of the index of a specified value ranked higher than an existing value in a NumPy array.

Sample Output:

Original array:

[-6 -5 -4 -3 -2 -1 0 1 2 3 4 5]

Position of the index:

9

Click me to see the sample solution

119. Add Row to Empty Array

Write a NumPy program to add another row to an empty NumPy array.

Sample Output:

Empty array:

[]

After adding two new arrays:

[[10 20 30]
[40 50 60]]

Click me to see the sample solution

120. Get Index of Max Element Along Axis

Write a NumPy program to get the index of a maximum element in a NumPy array along one axis.

Sample Output:

Original array:

[[1 2 3]
[4 3 1]]

Index of a maximum element in a NumPy array along one axis:

4

Click me to see the sample solution

121. Join Arrays Along New Axis

Write a NumPy program to join a sequence of arrays along an axis.

Sample Output:

Original arrays:

[1 2 3]
[2 3 4]

Sequence of arrays along a new axis:

[[1 2 3]
[2 3 4]]

Original arrays:

[[1]
[2]
[3]]
[[2]
[3]
[4]]

Sequence of arrays along a new axis:

[[1]
[2]
[3]
[2]
[3]
[4]]

Click me to see the sample solution

122. Index of Sliced Elements in Array

Write a NumPy program to find the index of the sliced elements from a given 4x4 array.

Sample Output:

Original arrays:
[[ 0 1 2 3]
........
[12 13 14 15]]

Sliced elements:
[ 0 5 11]

Click me to see the sample solution

123. Resize Array to Bigger and Smaller Sizes

Write a NumPy program to create two arrays bigger and smaller than a given array.

Sample Output:

Original arrays:
[[ 0 1 2 3]
........
[12 13 14 15]]

Array with size 2x2 from the said array:
[[0 1]
[2 3]]

Array with size 6x6 from the said array:
[[ 0 1 2 3 4 5]
.........
[14 15 0 1 2 3]]

Click me to see the sample solution

124. Broadcast Two Arrays (Shape (3,3) + (3))

Write a NumPy program to broadcast on different shapes of arrays where p(3,3) + q(3).

Sample Output:

Original arrays:

Array-1
[[0 0 0]
[1 2 3]
[4 5 6]]

Array-2
[10 11 12]

New Array:
[[10 11 12]
[11 13 15]
[14 16 18]]

Click me to see the sample solution

125. Broadcast Arrays (Shape (,3) + (3))

Write a NumPy program to broadcast on different shapes of arrays where a(,3) + b(3).

Sample Output:

Original arrays:

Array-1
[[ 0]
[10]
[20]]

Array-2
[10 11 12]

New Array:
[[10 11 12]
[20 21 22]
[30 31 32]]

Click me to see the sample solution

126. Rearrange Array Dimensions

Write a NumPy program to rearrange array dimensions.

Sample Output:

Original arrays:
[[ 0 1 2 3]
...........
[20 21 22 23]]

After reverse the dimensions:
[[ 0 4 8 12 16 20]
............
[ 3 7 11 15 19 23]]

Click me to see the sample solution

127. Stack Arrays Horizontally

Write a NumPy program to stack arrays horizontally (column wise).

Sample Output:

Original arrays:

Array-1
[[0 1 2]
[3 4 5]
[6 7 8]]

Array-2
[[ 0 3 6]
[ 9 12 15]
[18 21 24]]

Stack arrays in sequence horizontally:
[[ 0 1 2 0 3 6]
[ 3 4 5 9 12 15]
[ 6 7 8 18 21 24]]

Click me to see the sample solution

128. Stack Arrays Vertically

Write a NumPy program to stack arrays vertically.

Sample Output:

Original arrays:

Array-1
[[0 1 2]
[3 4 5]
[6 7 8]]

Array-2
[[ 0 3 6]
[ 9 12 15]
[18 21 24]]

Stack arrays in sequence vertically:
[[ 0 1 2]
...........
[18 21 24]]

Click me to see the sample solution

129. Stack 1D Arrays as Columns

Write a NumPy program to stack 1-D arrays columns wise.

Sample Output:

Original arrays:

Array-1
[1 2 3]

Array-2
[2 3 4]

Stack 1-D arrays as columns wise:
[[1 2]
[2 3]
[3 4]]

Click me to see the sample solution

130. Stack 1D Arrays as Rows

Write a NumPy program to stack 1-D arrays row wise.

Sample Output:

Original arrays:

Array-1
[1 2 3]

Array-2
[2 3 4]

Stack 1-D arrays as rows wise:
[[1 2 3]
[2 3 4]]

Click me to see the sample solution

131. Split Array Vertically

Write a NumPy program to split a given array into multiple sub-arrays vertically (row-wise).

Sample Output:

Original arrays:
[[ 0. 1. 2. 3.]
.............
[12. 13. 14. 15.]]

Split an array into multiple sub-arrays vertically:

[array([[0., 1., 2., 3.],
[4., 5., 6., 7.]]), array([[ 8., 9., 10., 11.],
[12., 13., 14., 15.]])]

Click me to see the sample solution

132. Split Array Along 3rd Axis

Write a NumPy program to split an array into multiple sub-arrays along the 3rd axis.

Sample Output:

Original arrays:
[[[ 0. 1. 2. 3.]
[ 4. 5. 6. 7.]]
[[ 8. 9. 10. 11.]
[12. 13. 14. 15.]]]

split array into multiple sub-arrays along the 3rd axis:
[array([[[ 0., 1.],
[ 4., 5.]],
[[ 8., 9.],
[12., 13.]]]),

array([[[ 2., 3.],
[ 6., 7.]],
[[10., 11.],
[14., 15.]]])]

Click me to see the sample solution

133. Count Dimensions, Elements, and Bytes of Array

Write a NumPy program to count the number of dimensions, number of elements and number of bytes for each element in a given array.

Sample Output:

Original arrays:

[[ 0 1 2 3 4 5 6 7 8 9 10 11]
[12 13 14 15 16 17 18 19 20 21 22 23]]

Number of dimensions:
2

Number of elements:
24

Number of bytes for each element in the said array:
8

Click me to see the sample solution

134. Extract First Row of 4x4 Array

Write a NumPy program to extract all the elements of the first row from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: First row
[0 1 2 3]

Click me to see the sample solution

135. Extract Second Row of 4x4 Array

Write a NumPy program to extract all the elements of the second row from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: Second row
[4 5 6 7]

Click me to see the sample solution

136. Extract Third Column of 4x4 Array

Write a NumPy program to extract all the third column elements from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: Third column
[ 2 6 10 14]

Click me to see the sample solution

137. Extract First & Second Elements of First Two Rows

Write a NumPy program to extract the first and second elements of the first and second rows from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: First and second elements of the first and second rows
[[0 1]
[4 5]]

Click me to see the sample solution

138. Extract Third & Fourth Elements of First Two Rows

Write a NumPy program to extract the third and fourth elements of the first and second rows from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: Third and fourth elements of the first and second rows
[[2 3]
[6 7]]

Click me to see the sample solution

139. Extract First & Third Elements of First/Third Rows

Write a NumPy program to extract the first and third elements of the first and third rows from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: First and third elements of the first and third rows
[[ 0 2]
[ 8 10]]

Click me to see the sample solution

140. Extract Second & Fourth Elements of Second/Fourth Rows

Write a NumPy program to extract the second and fourth elements of the second and fourth rows from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: Second and fourth elements of the second and fourth rows
[[ 5 7]
[13 15]]

Click me to see the sample solution

141. Extract Second & Third Columns

Write a NumPy program to extract all the elements of the second and third columns from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: All the elements of the second and third columns
[[ 1 2]
[ 5 6]
[ 9 10]
[13 14]]

Click me to see the sample solution

142. Extract First & Fourth Columns

Write a NumPy program to extract all the elements of the first and fourth columns from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: All the elements of the first and fourth columns
[[ 0 3]
[ 4 7]
[ 8 11]
[12 15]]

Click me to see the sample solution

143. Extract First Element of Second Row & Fourth of Fourth Row

Write a NumPy program to extract the first element of the second row and the fourth element of the fourth row from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: First element of the second row and fourth element of fourth row
[ 4 15]

Click me to see the sample solution

144. Extract Second & Third Elements of Second & Third Rows

Write a NumPy program to extract the second and third elements of the second and third rows from a given (4x4) array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Extracted data: Second and third elements of the second and third rows
[[ 5 6]
[ 9 10]]

Click me to see the sample solution

145. Extract First, Third, Fifth Elements of Third/Fifth Rows of 6x6 Array

Write a NumPy program to extract the first, third and fifth elements of the third and fifth rows from a given (6x6) array.

Sample Output:

Original array:
[[ 0 1 2 3 4 5]
................
[30 31 32 33 34 35]]

Extracted data: First, third and fifth elements of the third and fifth rows
[[12 14 16]
[24 26 28]]

Click me to see the sample solution

146. Add Arrays A (3,3) and B (,3)

Write a NumPy program to add two arrays A and B of sizes (3,3) and (,3).

Sample Output:

Original array:

Array-1
[[1. 1. 1.]
[1. 1. 1.]
[1. 1. 1.]]

Array-2
[0 1 2]

A + B:
[[1. 2. 3.]
[1. 2. 3.]
[1. 2. 3.]]

Click me to see the sample solution

147. Rank Items in Array

Write a NumPy program to create an array that represents the rank of each item in a given array.

Sample Output:

Original array:
[24 27 30 29 18 14]

Rank of each item of the said array:
[2 3 5 4 1 0]

Click me to see the sample solution

148. Copy Data to Another Array

Write a NumPy program to copy data from a given array to another array.

Sample Output:

Original array:
[24 27 30 29 18 14]

Copy of the said array:
[24 27 30 29 18 14]

Click me to see the sample solution

149. Find Elements in a Specified Range

Write a NumPy program to find elements within a range from a given array of numbers.

Sample Output:

Original array:
[ 1 3 7 9 10 13 14 17 29]

Elements within range: index position
(array([2, 3, 4, 5, 6, 7]),)

Click me to see the sample solution

150. Swap Columns in 2D Array

Write a NumPy program to swap columns in a given array.

Sample Output:

Original array:
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]]

After swapping arrays:
[[ 1 0 2 3]
[ 5 4 6 7]
[ 9 8 10 11]]

Click me to see the sample solution

151. Get rows where elements are larger than a specified value.

Write a NumPy program to get the row numbers in a given array where at least one item is larger than a specified value.

Sample Output:

Original array:
[[ 0 1 2 3 4 5 6 7 8]
[ 9 10 11 12 13 14 15 16 17]
[18 19 20 21 22 23 24 25 26]
[27 28 29 30 31 32 33 34 35]]

Row numbers where at least one item is larger than 10:
(array([1, 2, 3]),)

Click me to see the sample solution

152. Sum all columns of a 2D array.

Write a NumPy program to calculate the sum of all columns in a 2D NumPy array

Sample Output:

Original array:
[[ 0 1 2 3 4 5 6 7 8]
[ 9 10 11 12 13 14 15 16 17]
[18 19 20 21 22 23 24 25 26]
[27 28 29 30 31 32 33 34 35]]

Sum of all columns:
[54 58 62 66 70 74 78 82 86]

Click me to see the sample solution

153. Extract upper triangular part of a matrix.

Write a NumPy program to extract the upper triangular part of a NumPy matrix.

Sample Output:
Original array:
[[ 0 1 2]
...........
[15 16 17]]

Extract upper triangular part of the said array:
[0 1 2 4 5 8]

Extract upper triangular part of the said array:
[0 1 4]

Click me to see the sample solution

154. Zero out elements below k-th diagonal.

Write a NumPy program to get a copy of a matrix with the elements below the k-th diagonal zeroed.

Sample Output:

Original array:
[[1 2 3]
[0 5 6]
[0 0 9]
[0 0 0]]

Copy of a matrix with the elements below the k-th diagonal zeroed:
[[1 2 3]
[0 5 6]
[0 0 9]
[0 0 0]]

Click me to see the sample solution

155. Check if an array contains a specified row.

Write a NumPy program to check whether a Numpy array contains a specified row.

Sample Output:

Original array:
[[ 0 1 2 3 4]
[ 5 6 7 8 9]
[10 11 12 13 14]
[15 16 17 18 19]]

True
False
True

Click me to see the sample solution

156. Calculate averages without NaN.

Write a NumPy program to calculate averages without NaNs along a given array.

Sample Output:

Original array:
[[10. 20. 30.]
[40. 50. nan]
[nan 6. nan]
[nan nan nan]]

Averages without NaNs along the said array:
[20. 45. 6. nan]

Click me to see the sample solution

157. Average every consecutive triplet in an array.

Write a NumPy program to create an array which is the average of every consecutive triplet of elements in a given array.

Sample Output:

Original array:
[ 1 2 3 2 4 6 1 2 12 0 -12 6]

Average of every consecutive triplet of elements of the said array:
[ 2. 4. 5. -2.]

Click me to see the sample solution

158. Calculate average values of two arrays.

Write a NumPy program to calculate the average values of two given NumPy arrays.

Sample Output:

Original arrays:
[[0, 1], [2, 3]]
[[4, 5], [0, 3]]

Average values of two said NumPy arrays:
[[2. 3.]
[1. 3.]]

Click me to see the sample solution

159. Rearrange columns of a 2D array using indices.

Write a NumPy program to rearrange columns of a given NumPy 2D array using given index positions.

Sample Output:

Original arrays:
[[ 11 22 33 44 55]
[ 66 77 88 99 100]]

New array:
[[ 22 44 11 55 33]
[ 77 99 66 100 88]]

Click me to see the sample solution

160. Find k smallest values in an array.

Write a NumPy program to find the k smallest values in an array.

Sample Output:

Original arrays:
[ 1. 7. 8. 2. 0.1 3. 15. 2.5]

k smallest values:
[0.1 1. 2. 2.5]

Click me to see the sample solution

161. Create a white image of size 512x256.

Write a NumPy program to create a white image of size 512x256.

Sample Output:

Click me to see the sample solution

162. Extract elements from a specific axis using an index array.

Write a NumPy program to select from the first axis (K) by the indices tidx to get an array of shape (J=4, I=8) back.

Sample Output:

Original array and shape:
[[[3 2 2 7 7 7 0 3]
[5 8 4 2 9 9 3 9]
[6 8 2 8 5 7 8 7]
[5 2 4 0 4 9 2 5]]
------------------

tidex: [0 2 2 2]

Result:
[[3 2 2 7 7 7 0 3]
[3 9 2 6 3 3 1 0]
[5 4 0 6 0 2 7 8]
[6 3 1 8 8 1 5 7]]

Click me to see the sample solution

163. Count instances of values based on conditions.

Create two arrays of six elements. Write a NumPy program to count the number of instances of a value occurring in one array on the condition of another array.

Sample Output:

Original arrays:
[ 10 -10 10 -10 -10 10]
[0.85 0.45 0.9 0.8 0.12 0.6 ]

Number of instances of a value occurring in one array on the condition of another array:
3

Click me to see the sample solution

164. Save a matrix with mixed data types as text.

Write a NumPy program to save as text a matrix that has two floats in each row and one string at the end.

Sample Output:

string
1 0 aaa
0 1 bbb
0 1 ccc

Click me to see the sample solution

165. Merge three arrays of the same shape.

Write a NumPy program to merge three NumPy arrays of the same shape.

Click me to see the sample solution

166. Combine the last element of one array with the first of another.

Write a NumPy program to combine the last element with the first element of two given ndarray with different shapes.

Sample Output:

Original arrays:
['PHP', 'JS', 'C++']
['Python', 'C#', 'NumPy']

After Combining:
['PHP' 'JS' 'C++Python' 'C#' 'NumPy']

Click me to see the sample solution

167. Convert a Python dictionary to a NumPy array.

Write a NumPy program to convert a Python dictionary to a NumPy ndarray.

Sample Output:

Original dictionary:
{'column0': {'a': 1, 'b': 0.0, 'c': 0.0, 'd': 2.0},
'column1': {'a': 3.0, 'b': 1, 'c': 0.0, 'd': -1.0},
'column2': {'a': 4, 'b': 1, 'c': 5.0, 'd': -1.0},
'column3': {'a': 3.0, 'b': -1.0, 'c': -1.0, 'd': -1.0}}

Type: <class 'dict'>

ndarray:
[[ 1. 0. 0. 2.]
[ 3. 1. 0. -1.]
[ 4. 1. 5. -1.]
[ 3. -1. -1. -1.]]

Type: <class 'numpy.ndarray'>

Click me to see the sample solution

168. Convert Pandas DataFrame to NumPy array with headers.

Write a NumPy program to convert Pandas dataframe to a NumPy array with headers

Sample Output:

Original NumPy array:
[[0.18308157 0.32258608 0.39644848]
[0.31018507 0.08220454 0.40018982]
[0.63639779 0.34908174 0.39878868]
............
[0.02482073 0.02318678 0.36032194]
[0.69001834 0.04285817 0.31768865]]

Type: <class 'numpy.ndarray'>

Panda's DataFrame:
A B C
0 0.015583 0.968431 0.943192
1 0.221607 0.704098 0.241200
2 0.466129 0.269226 0.450781
3 0.747222 0.674508 0.686070
............
10 0.272827 0.817238 0.093650
11 0.196416 0.643602 0.262683

Type: <class 'pandas.core.frame.DataFrame'>

Click me to see the sample solution

169. Extract all 2D diagonals of a 3D array.

Write a NumPy program to get all 2D diagonals of a 3D NumPy array.

Sample Output:

Original NumPy array:
[[[ 0 1 2 3 4]
[ 5 6 7 8 9]
[10 11 12 13 14]
[15 16 17 18 19]]
............
[[40 41 42 43 44]
[45 46 47 48 49]
[50 51 52 53 54]
[55 56 57 58 59]]]

Type: <class 'numpy.ndarray'>

2D diagonals:
[[ 0 6 12 18]
[20 26 32 38]
[40 46 52 58]]

Type: <class 'numpy.ndarray'>

Click me to see the sample solution

170. Count occurrences of sequences in a 2D array.

Create a 2-dimensional array of size 2 x 3, composed of 4-byte integer elements. Write a NumPy program to find the number of occurrences of a sequence in an array.

Sample Output:

Original NumPy array:
[[1 2 3]
[2 1 2]]

Type: <class 'numpy.ndarray'>

Sequence: 2,3

Number of occurrences of the said sequence: 2

Click me to see the sample solution

171. Search for a sub-array in a larger array.

Write a NumPy program to search for the index of a given array in a different array.

Sample Output:

Original NumPy array:
[[ 1 2 3]
[ 4 5 6]
[ 7 8 9]
[10 11 12]]

Searched array:
[4 5 6]

Index of the searched array in the original array:
[1]

Click me to see the sample solution

172. Store non-zero unique rows from a matrix.

Write a NumPy program to find and store non-zero unique rows in an array after comparing each row with other rows in a given matrix.

Sample Output:

Original array:
[[ 1 1 0]
[ 0 0 0]
[ 0 2 3]
[ 0 0 0]
[ 0 -1 1]
[ 0 0 0]]

Non-zero unique rows:
[[ 1 1 0]
[ 0 2 3]
[ 0 -1 1]]

Click me to see the sample solution

173. Set lower triangles of a 3D array to zero.

Write a NumPy program to set zero to lower triangles along the last two axes of a three-dimensional of a given array.

Sample Output:

Original array:
[[[1. 1. 1. 1. 1. 1. 1. 1.]
[1. 1. 1. 1. 1. 1. 1. 1.]
..............
[1. 1. 1. 1. 1. 1. 1. 1.]]]

Result:
[[[0. 1. 1. 1. 1. 1. 1. 1.]
[0. 0. 1. 1. 1. 1. 1. 1.]
.................
[0. 0. 0. 0. 0. 0. 0. 0.]]]

Click me to see the sample solution

174. Get array metadata (dimensions, size, etc.).

Write a NumPy program to get the number of items, array dimensions, number of array dimensions and the memory size of each element of a given array.

Sample Output:

Original array:
[[ 1 2 3 4]
[ 5 6 7 8]
[ 9 10 11 12]]

Number of items of the said array:
12

Array dimensions:
(3, 4)

Number of array dimensions:
2

Memory size of each element of the said array
8

Click me to see the sample solution

175. Reshape 1D array to 2D and restore.

Write a NumPy program to create a 1-D array of 20 elements. Now creates an array of shapes (5, 4) from the said array, then restore the reshaped array into a 1-D array.

Sample Output:

Original array:
[ 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38]

New array of shape(5, 3):
[[ 0 2 4 6]
[ 8 10 12 14]
[16 18 20 22]
[24 26 28 30]
[32 34 36 38]]

Restore the reshaped array into a 1-D array:
[ 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38]

Click me to see the sample solution

176. Swap specific columns in a 2D array.

Write a NumPy program to create an array of shapes 4,5 and swap column1 with column4.

Sample Output:

Original array:
[[ 0 1 2 3 4]
[ 5 6 7 8 9]
[10 11 12 13 14]
[15 16 17 18 19]]

After swapping column1 with column4:
[[ 3 1 2 0 4]
[ 8 6 7 5 9]
[13 11 12 10 14]
[18 16 17 15 19]]

Click me to see the sample solution

177. Reverse the rows of a 2D array.

Write a NumPy program to create an array of 4,5 shaped arrays and reverse the rows of that array. After reversing 1st row will be 4th row and 4th row will be 1st row, 2nd row will be 3rd row and 3rd row will be 2nd row.

Sample Output:

Original array:
[[ 0 1 2 3 4]
[ 5 6 7 8 9]
[10 11 12 13 14]
[15 16 17 18 19]]

After reversing:
[[15 16 17 18 19]
[10 11 12 13 14]
[ 5 6 7 8 9]
[ 0 1 2 3 4]]

Click me to see the sample solution

178. Replace NaN values with the mean of another array.

Write a NumPy program to replace all the nan (missing values) of a given array with the mean of another array.

Sample Output:

Original arrays:
[[ 0 1 2 3 4]
[ 5 6 7 8 9]
[10 11 12 13 14]
[15 16 17 18 19]]
[[ 1. 2. nan]
[ 4. 5. 6.]
[nan 7. nan]]

All the nan of array_nums2 replaced by the mean of array_nums1:
[[1. 2. 9.5]
[4. 5. 6. ]
[9.5 7. 9.5]]

Click me to see the sample solution

179. Extract items greater than 6 and multiples of 3.

Write a NumPy program to fetch all items from a given array of shape 4,5 which are greater than 6 and a multiple of 3.

Sample Output:

Original arrays:
[[ 0 1 2 3 4]
[ 5 6 7 8 9]
[10 11 12 13 14]
[15 16 17 18 19]]

Items greater than 6 and a multiple of 3 of the said array:
[ 9 12 15 18]

Click me to see the sample solution

180. Check if dimensions of two arrays match.

Write a NumPy program to check whether the dimensions of two given arrays are the same or not.

Click me to see the sample solution

181. Place elements randomly in a 2D array.

Write a NumPy program to place a specified element at a specified time randomly in a specified 2D array.

Sample Output:

Original array:
[[0. 0. 0. 0.]
[0. 0. 0. 0.]
[0. 0. 0. 0.]
[0. 0. 0. 0.]]

Place a specified element in specified time randomly:
[[10. 0. 0. 0.]
[10. 0. 0. 0.]
[ 0. 0. 0. 10.]
[ 0. 0. 0. 0.]]

Click me to see the sample solution

182. Subtract mean of each row from a matrix.

Write a NumPy program to subtract the mean of each row from a given matrix.

Sample Output:

Original matrix:
[[0.59243452 0.51883289 0.03732848 0.49544926 0.22637201 0.45750412
0.81614237 0.86681236 0.95482226 0.54789281]
..............
[0.14428353 0.20556412 0.97059136 0.53545871 0.93828877 0.81535277
0.60563373 0.47543413 0.0468766 0.97460889]]

Subtract the mean of each row of the said matrix:
[[ 0.04107541 -0.03252622 -0.51403063 -0.05590985 -0.3249871 -0.09385499
0.26478326 0.31545325 0.40346315 -0.0034663 ]
....................
[-0.42692573 -0.36564514 0.3993821 -0.03575056 0.36707951 0.24414351
0.03442447 -0.09577513 -0.52433266 0.40339963]]

Click me to see the sample solution

183. Check if a 2D array has null columns.

Write a NumPy program to test whether a 2D array has null columns or not.

Sample Output:

Original array:
[[1 2 1 1 1 2 1 1 2 0]
[1 1 0 0 0 0 2 1 2 0]
[0 0 2 1 0 2 2 2 2 2]
[1 1 1 2 0 0 0 0 1 2]]

Test whether the said array has null columns or not:
False

Click me to see the sample solution

184. Create array using generator function.

Write a NumPy program to create an array using a generator function that generates 15 integers.

Sample Output:

New array:
[ 0. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.]

Click me to see the sample solution

185. Insert zeros between elements in an array.

Write a NumPy program to create a vector with 2 consecutive 0 between two values of a given vector.

Sample Output:

Original array:
[1 2 3 4 5 6 7 8]

New array:
[1. 0. 0. 2. 0. 0. 3. 0. 0. 4. 0. 0. 5. 0. 0. 6. 0. 0. 7. 0. 0. 8.]

Click me to see the sample solution

186. Multiply arrays of compatible dimensions.

Write a NumPy program to multiply an array of dimensions (2,2,3) by an array with dimensions (2,2).

Sample Output:

Original array:
[[[1. 1. 1.]
[1. 1. 1.]]
[[1. 1. 1.]
[1. 1. 1.]]]

New array:
[[[3. 3. 3.]
[3. 3. 3.]]
[[3. 3. 3.]
[3. 3. 3.]]]

Click me to see the sample solution

187. Convert integer vector to binary matrix.

Write a NumPy program to convert a given vector of integers to a binary matrix.

Sample Output:

Original vector:
[ 0 1 3 5 7 9 11 13 15]

Binary representation of the said vector:
[[0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 1]
..............
[0 0 0 0 1 1 1 1]]

Click me to see the sample solution

188. Extract rows with unequal values.

Write a NumPy program to extract rows with unequal values (e.g. [1,1,2]) from a 10x3 matrix.

Sample Output:

Original vector:
[[3 2 0]
........
[3 0 2]]

Rows with unequal values:
[[3 2 0]
[2 3 1]
.........
[3 0 2]]

Click me to see the sample solution

189. Find rows containing elements of another array.

Write a NumPy program to find rows of a given array of shape (8,3) that contain elements of each row of another given array of shape (2,2).

Sample Output:

Original arrays:
[[5 2 5 1]
[5 4 1 3]
..........
[4 0 4 0]]
[[2 3 1]
[1 1 4]]

Rows of a given array that contain elements of each row of another given array:
[0 1 2 4]

Click me to see the sample solution

190. Create a record array from a regular array.

Write a NumPy program to create a record array from a given regular array.

Sample Output:

Original arrays:
[['Yasemin Rayner' '88.5' '90']
['Ayaana Mcnamara' '87' '99']
['Jody Preece' '85.5' '91']]

Record array;
[(b'Yasemin Rayner', 88.5, 90) (b'Ayaana Mcnamara', 87. , 99)
(b'Jody Preece', 85.5, 91)]

Click me to see the sample solution

191. Compute block-sum of a 25x25 matrix (e.g., sum of each 5x5 block).

Write a NumPy program to get the block-sum (block size is 5x5) from a given array of shape 25x25.

Sample Output:

Original arrays:
[[1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]
[1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]
.........................
[1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1.]]

Block-sum (5x5) of the said array:
[[25. 25. 25. 25. 25.]
[25. 25. 25. 25. 25.]
[25. 25. 25. 25. 25.]
[25. 25. 25. 25. 25.]
[25. 25. 25. 25. 25.]]

Click me to see the sample solution

192. Extract all contiguous 4x4 blocks from a 12x12 matrix.

Write a NumPy program to extract all the contiguous 4x4 blocks from a given random 12x12 matrix.

Sample Output:

Original arrays:
[[3 3 1 2 0 3 0 3 2 0 1 0]
[4 0 4 2 0 0 0 0 2 2 2 3]
..................
[1 2 3 4 1 2 3 4 3 2 3 4]
[4 0 4 2 2 4 1 4 2 0 0 0]]

Contiguous 4x4 blocks:
[[[[3 3 1 2]
[4 0 4 2]
[1 4 0 1]
[1 4 2 4]]
...
[[4 1 1 0]
[1 0 2 2]
[3 2 3 4]
[2 0 0 0]]]]

Click me to see the sample solution

193. Compare speed of NumPy array vs Python list.

Write a Numpy program to test whether a numpy array is faster than a Python list or not.

Time to aggregates elements from each of the iterables:

Sample Output:

List:
72.64399528503418

NumPy array:
19.61684226989746

Click me to see the sample solution

194. Combine two arrays into one after inserting an axis.

Write a NumPy program to create two arrays with shape (300,400, 5). Fill values with unsigned integers (0 to 255). Insert an axis at the beginning of the expanded array shape. Now combine both arrays into one.

Sample Output:

Array1:
[[[ 46 117 73]
[215 90 86]
[ 80 89 220]
...
[ 47 94 234]
[ 95 72 61]
[154 91 175]]
[[232 194 26]
[219 116 116]
[126 179 177]
...

Array2:
[[[ 37 10 228]
[241 52 82]
[196 47 189]
...
[127 70 246]
[158 46 12]
[ 56 129 162]]
[[224 215 47]
[139 72 13]
[218 64 78]
...

Combined array:
[[[[ 46 117 73]
[215 90 86]
[ 80 89 220]
...
[208 187 55]
[109 115 254]
[115 134 68]]
[[158 106 165]
[189 48 54]
[ 5 84 26]
...
[131 235 25]
[101 146 90]
[216 15 92]]]]

Click me to see the sample solution

195. Remove first dimension of a (1,3,4) array.

Write a NumPy program to remove the first dimension from a given array of shape (1,3,4).

Sample Output:

Shape of the said array:
(1, 3, 4)

After removing the first dimension of the shape of the said array:

Click me to see the sample solution

196. Extract shape (6,6,3) array from a 12x12x4 matrix.

Write a NumPy program to create a 12x12x4 array with random values and extract any array of shape(6,6,3) from the said array.

Sample Output:

Original array:
[[[0.67420382 0.5592584 0.27096382]
[0.2896283 0.68346522 0.13996167]
[0.74283318 0.06323309 0.0980022 ]
[0.43203954 0.38888969 0.44801756]
[0.04391897 0.4851516 0.34044817]
[0.2202623 0.81434798 0.51900666]
[0.12442371 0.91247823 0.01874549]
[0.2287782 0.88089638 0.40583551]]
........
[[0.28021231 0.47537742 0.72971633]
[0.87380873 0.83031311 0.56713737]
[0.23093306 0.22830678 0.54439754]
[0.88130002 0.37081258 0.78148687]
[0.00318428 0.62297164 0.58875116]
[0.68102061 0.31822913 0.04432477]
[0.70410386 0.56770957 0.42998752]
[0.5891714 0.25692428 0.19184309]]]

Extract array of shape (6,6,3) from the said array:
[[[0.67420382 0.5592584 0.27096382]
[0.2896283 0.68346522 0.13996167]
[0.74283318 0.06323309 0.0980022 ]
[0.43203954 0.38888969 0.44801756]
[0.04391897 0.4851516 0.34044817]
[0.2202623 0.81434798 0.51900666]]
.......
[[0.85965509 0.11357479 0.27325381]
[0.74156642 0.35108524 0.40305073]
[0.44791592 0.28270286 0.45377936]
[0.01543443 0.14978493 0.47738367]
[0.63671823 0.75239388 0.59118693]
[0.55932007 0.32759274 0.25519358]]]

Click me to see the sample solution

197. Concatenate arrays with different shapes.

Write a NumPy program to create a concatenation of two given arrays of shapes (2, 2) and (2,1).

Sample Output:

Original arrays:
[[4.5 3.5]
[5.1 2.3]]
[[1]
[2]]

Concatenating the said two arrays:
[[4.5 3.5 1. ]
[5.1 2.3 2. ]]

Click me to see the sample solution

198. Create a random 10x4 array with precision control.

Write a NumPy program to create a 10x4 array filled with random floating point number values. Set the array values with the specified precision.

Sample Output:

Original arrays:
[[-1.23335604 0.54368124 1.93500931 -0.45001639]
[ 1.20528013 2.04423279 -0.68858903 -0.46642789]
[ 1.29030601 0.60914425 0.03139104 -1.72528221]
[-0.32607231 -2.36951679 -0.80374203 -0.26212641]
[-0.16426628 -0.21524949 -0.35957311 -2.27709735]
[-0.28851276 -0.59101441 0.22293919 -0.50128832]
[ 1.3577567 0.05529019 0.81208832 0.70810424]
[ 0.46853801 -0.81857981 0.80443323 0.52391606]
[-0.29149088 -0.91153449 -1.00515549 0.31065165]
[ 2.68952752 1.86676839 1.49239198 -1.0409156 ]]

Set the array values with specified precision:
[[-1.2334 0.5437 1.935 -0.45 ]
[ 1.2053 2.0442 -0.6886 -0.4664]
[ 1.2903 0.6091 0.0314 -1.7253]
[-0.3261 -2.3695 -0.8037 -0.2621]
[-0.1643 -0.2152 -0.3596 -2.2771]
[-0.2885 -0.591 0.2229 -0.5013]
[ 1.3578 0.0553 0.8121 0.7081]
[ 0.4685 -0.8186 0.8044 0.5239]
[-0.2915 -0.9115 -1.0052 0.3107]
[ 2.6895 1.8668 1.4924 -1.0409]]

Click me to see the sample solution

199. Represent values in scientific notation with precision.

Write a NumPy program to create an array using scientific notation for numbers. Set the precision value to 6 and print the array.

Sample Output:

Original arrays:
[1.2e-07 1.5e-06 1.7e-05]
Set the precision value to 10:
[0.00000012 0.0000015 0.000017 ]

Click me to see the sample solution

200. Remove specific columns from a 2D array.

Write a NumPy program to remove a specific column from a given array.

Sample Output:

Original array:
[[0.54420704 0.35710194 0.79167579 0.72249474 0.99968936]
[0.22306352 0.31085825 0.09849254 0.11708716 0.45757945]
[0.19381592 0.13587749 0.90455038 0.95146017 0.55716851]
[0.62031347 0.84275698 0.84665943 0.06562172 0.58415968]
[0.41903059 0.0660559 0.85270403 0.94184265 0.95371587]
[0.02577681 0.91577282 0.1969686 0.3472482 0.23337827]
[0.43563908 0.62308811 0.09606371 0.79053989 0.69382428]]

Delete the first column of the said array:
[[0.35710194 0.79167579 0.72249474 0.99968936]
[0.31085825 0.09849254 0.11708716 0.45757945]
[0.13587749 0.90455038 0.95146017 0.55716851]
[0.84275698 0.84665943 0.06562172 0.58415968]
[0.0660559 0.85270403 0.94184265 0.95371587]
[0.91577282 0.1969686 0.3472482 0.23337827]
[0.62308811 0.09606371 0.79053989 0.69382428]]

Delete the last column of the said array:
[[0.54420704 0.35710194 0.79167579 0.72249474]
[0.22306352 0.31085825 0.09849254 0.11708716]
[0.19381592 0.13587749 0.90455038 0.95146017]
[0.62031347 0.84275698 0.84665943 0.06562172]
[0.41903059 0.0660559 0.85270403 0.94184265]
[0.02577681 0.91577282 0.1969686 0.3472482 ]
[0.43563908 0.62308811 0.09606371 0.79053989]]

Click me to see the sample solution

201. Print extended edges of a random 90x30 array.

Write a NumPy program to create a 90x30 array filled with random point numbers. Increase the number of items (10 edge elements) shown in the print statement.

Sample Output:

Original array:
[[1 8 3 ... 9 5 8]
[1 9 6 ... 6 5 0]
[0 0 8 ... 6 9 8]
...
[2 3 9 ... 4 0 1]
[2 6 8 ... 8 3 4]
[1 2 9 ... 7 4 8]]

Increase the number of items (10 edge elements) shown by the print statement:
[[1 8 3 0 1 2 8 0 0 5 ... 1 3 8 1 1 7 5 9 5 8]
[1 9 6 1 0 7 7 3 8 6 ... 5 9 9 9 9 7 2 6 5 0]
[0 0 8 1 4 2 1 3 2 9 ... 5 6 4 1 4 9 0 6 9 8]
[7 2 7 1 7 2 4 7 2 0 ... 4 2 6 2 6 4 4 0 6 7]
[3 6 0 0 2 1 6 6 2 9 ... 3 4 1 9 5 7 4 4 6 7]
[9 5 2 6 9 2 7 7 9 6 ... 4 3 5 2 7 0 6 0 2 7]
[5 5 4 1 9 2 5 3 5 2 ... 7 4 7 5 5 7 3 0 1 8]
[5 9 9 9 6 3 5 0 9 4 ... 6 4 9 7 8 7 2 5 9 4]
[6 1 0 8 9 8 0 6 6 3 ... 5 3 1 6 1 5 2 9 8 3]
[3 0 3 1 4 1 4 1 9 6 ... 3 9 4 4 5 0 2 0 8 0]
...
[3 9 5 0 3 8 5 3 1 1 ... 1 2 4 6 2 4 5 0 0 5]
[7 9 7 0 1 3 0 1 8 4 ... 5 7 5 4 7 2 0 2 3 0]
[4 2 6 4 7 2 3 9 7 9 ... 2 7 1 2 5 7 5 4 0 2]
[7 8 9 7 3 3 1 2 8 5 ... 1 9 9 5 5 2 3 5 0 1]
[3 7 6 8 3 2 5 0 5 4 ... 0 4 9 8 5 3 2 1 3 3]
[3 3 8 4 0 4 8 4 7 0 ... 7 5 0 9 7 8 2 0 7 9]
[8 4 4 7 3 8 2 0 8 9 ... 5 5 8 1 5 6 0 6 5 0]
[2 3 9 9 9 8 6 5 4 4 ... 4 0 7 1 8 6 7 4 0 1]
[2 6 8 7 3 3 8 4 1 6 ... 1 3 9 5 0 1 4 8 3 4]
[1 2 9 5 1 2 9 9 5 4 ... 3 1 2 6 1 4 4 7 4 8]]

Click me to see the sample solution

202. Compute element-wise arithmetic mean of two arrays.

Write a NumPy program to calculate the arithmetic mean of the corresponding elements of two given arrays of the same size.

Sample Output:

Array1:
[[2 5 2]
[1 5 5]]

Array2:
[[5 3 4]
[3 2 5]]

Arithmetic means of corresponding elements of said two arrays:
[[3.5 4. 3. ]
[2. 3.5 5. ]]

Click me to see the sample solution

203. Shuffle specific rows in a 11x3 student data array.

Write a NumPy program to create a 11x3 array filled with student information (id, class and name) and shuffle the rows of the array starting from 3rd to 9th.

Sample Output:

Original array:
[['stident_id' 'Class' 'Name']
['01' 'V' 'Debby Pramod']
['02' 'V' 'Artemiy Ellie']
['03' 'V' 'Baptist Kamal']
['04' 'V' 'Lavanya Davide']
['05' 'V' 'Fulton Antwan']
['06' 'V' 'Euanthe Sandeep']
['07' 'V' 'Endzela Sanda']
['08' 'V' 'Victoire Waman']
['09' 'V' 'Briar Nur']
['10' 'V' 'Rose Lykos']]

Shuffle the said array rows starting from 3rd to 9th
[['stident_id' 'Class' 'Name']
['01' 'V' 'Debby Pramod']
['02' 'V' 'Artemiy Ellie']
['03' 'V' 'Baptist Kamal']
['07' 'V' 'Endzela Sanda']
['04' 'V' 'Lavanya Davide']
['06' 'V' 'Euanthe Sandeep']
['05' 'V' 'Fulton Antwan']
['08' 'V' 'Victoire Waman']
['09' 'V' 'Briar Nur']
['10' 'V' 'Rose Lykos']]

Click me to see the sample solution

204. Extract rows based on column starting character.

Write a NumPy program to extract all the rows from a given array where a specific column starts with a given character.

Sample Output:

Original array:
[['01' 'V' 'Debby Pramod']
['02' 'V' 'Artemiy Ellie']
['03' 'V' 'Baptist Kamal']
['04' 'V' 'Lavanya Davide']
['05' 'V' 'Fulton Antwan']
['06' 'V' 'Euanthe Sandeep']
['07' 'V' 'Endzela Sanda']
['08' 'V' 'Victoire Waman']
['09' 'V' 'Briar Nur']
['10' 'V' 'Rose Lykos']]

Student name starting with E :
[['06' 'V' 'Euanthe Sandeep']
['07' 'V' 'Endzela Sanda']]

Student id starting with 1 :
[['10' 'V' 'Rose Lykos']]

Click me to see the sample solution

205. Compute weight sum of rows where names match a condition.

Write a NumPy program to extract all the rows to compute the student weight from a given array (student information) where a specific column starts with a given character.

Sample Output:

Original array:
[['01' 'V' 'Debby Pramod' '30.21']
['02' 'V' 'Artemiy Ellie' '29.32']
['03' 'V' 'Baptist Kamal' '31.0']
['04' 'V' 'Lavanya Davide' '30.22']
['05' 'V' 'Fulton Antwan' '30.21']
['06' 'V' 'Euanthe Sandeep' '31.0']
['07' 'V' 'Endzela Sanda' '32.0']
['08' 'V' 'Victoire Waman' '29.21']
['09' 'V' 'Briar Nur' '30.0']
['10' 'V' 'Rose Lykos' '32.0']]

Total weight, where student name starting with E
63.0

Total weight, where student name starting with D
30.21

Click me to see the sample solution

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