ValueError: all input arrays must have the same shape

ValueError: all input arrays must have the same shape

$ python -c "import numpy as np; a=np.zeros((2,2)); b=np.zeros((3,2)); np.concatenate([a,b])"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ValueError: all the input arrays must have same shape

Why this happens

Functions like np.stack require all inputs to have identical shapes along the concatenation axes.

Fix

Reshape, pad, or trim arrays to matching shapes or use concatenation along an axis that matches shapes.

Wrong code

import numpy as np
a = np.zeros((2,2))
b = np.zeros((3,2))
np.stack([a,b])

Fixed code

import numpy as np
a = np.zeros((2,2))
b = np.zeros((2,2))
np.stack([a,b])

# or concatenate along axis=0 if shapes match
np.concatenate([a,b[:2,:]], axis=0)