Join two 2D numpy array with one row over another

Question

Two numpy arrays, lets say

a = np.array([[1,2], [3,4]])
b = np.array([[5,6], [7,8]])

I would like to combine two arrays into one single array such that the results looks like below array

np.array([[1,2],
          [5,6],
          [3,4],
          [7,8]])

I tried using concatenate, merge function, but cannot able to find pythonic way to solve this. Is there is any in built function to solve my problem.

mozway · Accepted Answer · 2022-02-13 06:06:36Z

2

IIUC, you could stack on the first axis, and reshape:

np.stack((a,b), axis=1).reshape(-1,2)

Or use np.c_ and reshape:

np.c_[a,b].reshape((-1,2))

Output:

array([[1, 2],
       [5, 6],
       [3, 4],
       [7, 8]])

answered Feb 12, 2022 at 23:33

mozway

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1 Comment

Use the axis parameter to skip the swap: np.stack((a,b),axis=1).reshape(-1,2)

user7864386 · Accepted Answer · 2022-02-12 23:33:30Z

1

You can column_stack + reshape:

out = np.column_stack((a,b)).reshape(4,2)

Output:

array([[1, 2],
       [5, 6],
       [3, 4],
       [7, 8]])

answered Feb 12, 2022 at 23:33

user7864386