[Solved] Why does np.sum(arr, axis=1) raise an error if arr is a 1D array? — Ans: Because axis=1 is out of bounds for 1D arrays which only have axis 0. | NumPy

NumPy - Aggregation Functions

Why does np.sum(arr, axis=1) raise an error if arr is a 1D array?

ABecause axis must be a negative integer for 1D arrays.

BBecause np.sum does not support axis parameter for 1D arrays.

CBecause arr must be 2D to use np.sum.

DBecause axis=1 is out of bounds for 1D arrays which only have axis 0.

Step-by-Step Solution

Solution:

Step 1: Check dimensions of 1D array
A 1D array has only one axis: axis 0.
Step 2: Validate axis parameter
axis=1 is invalid for 1D arrays and causes an IndexError.
Final Answer:
Because axis=1 is out of bounds for 1D arrays which only have axis 0. -> Option D
Quick Check:
1D arrays have only axis 0 [OK]

Quick Trick: 1D arrays only have axis 0 [OK]

Common Mistakes:

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Why does np.sum(arr, axis=1) raise an error if arr is a 1D array?