NumPy: Combine last element with first element of two given ndarray with different shapes

Last update on April 26 2025 12:40:39 (UTC/GMT +8 hours)

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

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

Sample Solution:

Python Code:

# Importing the NumPy library
import numpy as np

# Creating two lists
array1 = ['PHP', 'JS', 'C++']
array2 = ['Python', 'C#', 'NumPy']

# Printing the original arrays
print("Original arrays:")
print(array1)
print(array2)

# Combining the arrays using np.r_
result = np.r_[array1[:-1], [array1[-1] + array2[0]], array2[1:]]

# Printing the combined result
print("\nAfter Combining:")
print(result)

Sample Output:

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

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

Explanation:

array1 = ['PHP','JS','C++']

array2 = ['Python','C#', 'NumPy']

The above two statements create two arrays ‘array1’ and ‘array2’ of two 1D arrays containing strings.

result = np.r_[array1[:-1], [array1[-1]+array2[0]], array2[1:]]

In the above code -

• array1[:-1] contains all elements of array1 except the last one, i.e., ['PHP', 'JS'].
• [array1[-1]+array2[0]] creates a new single-element array containing the concatenation of the last element of array1 and the first element of array2, i.e., ['C++Python'].
• array2[1:] contains all elements of array2 except the first one, i.e., ['C#', 'NumPy'].
• np.r_[...] concatenates the three parts (arrays) mentioned above along the first axis (axis=0). The resulting array is ['PHP', 'JS', 'C++Python', 'C#', 'NumPy'].

Pictorial Presentation:

For more Practice: Solve these Related Problems:

• Write a NumPy program to concatenate two 1D arrays by merging the last element of the first array with the first element of the second array.
• Create a function that removes the duplicate boundary element when combining two arrays and returns the merged result.
• Implement a solution that uses slicing to extract the required portions from both arrays before concatenation.
• Test the combination on arrays of different lengths to verify that the merged array contains the correct sequence.

Go to:

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• NumPy Exercises Home ↩

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