TypeError/ValueError: repeats must have same length as the array in np.repeat

TypeError/ValueError: repeats must have same length as the array in np.repeat

$ python - <<'PY'
import numpy as np
np.repeat(np.arange(3), repeats=[1, 2])
PY
Traceback (most recent call last):
  File "<string>", line 3, in <module>
ValueError: 'repeats' must have the same length as 'array' when 'repeats' is an array

Why this happens

When repeats is an array-like, np.repeat expects its length to match the array’s length along the axis being repeated. This gives a per-element repeat count. Passing a mismatched-length repeats raises an error.

Fix

Provide either a scalar repeats (one value applied to all elements) or an array of integers whose length matches arr.shape[axis].

Wrong code

import numpy as np
arr = np.arange(3)  # length 3
np.repeat(arr, repeats=[1, 2])  # ValueError

Fixed code

import numpy as np
arr = np.arange(3)
# scalar repeats
print(np.repeat(arr, 2))  # [0 0 1 1 2 2]
# array-like repeats with same length as arr
print(np.repeat(arr, [1, 2, 3]))  # [0, 1, 1, 2, 2, 2]