NumPy: Sort the specified number of elements from beginning of a given array
8. Partial Sorting from the Beginning of an Array
Write a NumPy program to sort the specified number of elements from beginning of a given array.
Sample Solution:
Python Code:
# Importing the NumPy library
import numpy as np
# Creating an array of 10 random numbers
nums = np.random.rand(10)
# Displaying the original array
print("Original array:")
print(nums)
# Sorting the first 5 elements using argpartition
print("\nSorted first 5 elements:")
print(nums[np.argpartition(nums, range(5))])
Sample Output:
Original array: [0.39536213 0.11779404 0.32612381 0.16327394 0.98837963 0.25510787 0.01398678 0.15188239 0.12057667 0.67278699] Sorted first 5 elements: [0.01398678 0.11779404 0.12057667 0.15188239 0.16327394 0.25510787 0.39536213 0.98837963 0.32612381 0.67278699]
Explanation:
nums = np.random.rand(10): This line creates a NumPy array nums containing 10 random float elements from a uniform distribution over [0, 1).
np.argpartition(nums, range(5)): This line uses the np.argpartition function to partition the indices of the array nums at the specified index positions, which in this case is a range from 0 to 4. The result is a new array of indices where the elements before the specified indices (0 to 4) are indices of smaller elements, and the elements after the indices are indices of larger elements. The order of the indices within each partition is not guaranteed to be sorted.
print(nums[np.argpartition(nums, range(5))]): This line prints the result of indexing the original nums array using the partitioned indices, which returns the smallest 5 elements from the original nums array.
Pictorial Presentation:
For more Practice: Solve these Related Problems:
- Sort only the first n elements of a 1D array while leaving the rest unsorted using a combination of np.partition and np.sort.
- Create a function that extracts the first n elements, sorts them, and then concatenates them back with the unsorted remainder.
- Implement a solution that performs in-place partial sorting on the beginning section of an array.
- Test the function on arrays of varying lengths to ensure that the partial sorting correctly modifies only the specified segment.
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Previous: Write a NumPy program to sort a given complex array using the real part first, then the imaginary part.
Next: Write a NumPy program to sort an given array by the nth column.
Python-Numpy Code Editor:
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