Horizontal (hstack) and Vertical (vstack) Stacking in NumPy

NumPy provides functions to stack arrays either horizontally or vertically. The two main functions used for this purpose are:

  • hstack() - Stacks arrays horizontally (column-wise).
  • vstack() - Stacks arrays vertically (row-wise).

1. Horizontal Stacking (hstack)

The hstack() function stacks arrays side by side along the second axis.

    import numpy as np
    
    arr1 = np.array([1, 2, 3])
    arr2 = np.array([4, 5, 6])
    hstacked_arr = np.hstack((arr1, arr2))
    print(hstacked_arr)

Output:

    [1 2 3 4 5 6]

2. Vertical Stacking (vstack)

The vstack() function stacks arrays on top of each other along the first axis.

    arr1 = np.array([1, 2, 3])
    arr2 = np.array([4, 5, 6])
    vstacked_arr = np.vstack((arr1, arr2))
    print(vstacked_arr)

Output:

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

Conclusion

Using hstack() and vstack(), we can easily combine arrays horizontally and vertically. These functions are useful for structuring data in a convenient way for further processing.




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