You want to normalize each column of a 2D numpy array by subtracting the column mean. Given arr shape (5,4), which code correctly uses broadcasting?

hard📝 Application Q9 of 15

NumPy - Broadcasting

Aarr - arr.mean(axis=0).reshape(5,1)

Barr - arr.mean(axis=1)

Carr - arr.mean(axis=1).reshape(1,4)

Darr - arr.mean(axis=0)

Step-by-Step Solution

Solution:

Step 1: Calculate column means
arr.mean(axis=0) returns shape (4,), the mean of each column.
Step 2: Subtract column means from arr
Subtracting (5,4) - (4,) broadcasts the means across rows, normalizing columns.
Step 3: Check other options
arr - arr.mean(axis=1) subtracts row means, incorrect. Options A and D reshape incorrectly causing errors.
Final Answer:
arr - arr.mean(axis=0) -> Option D
Quick Check:
Subtract column means with axis=0 mean [OK]

Quick Trick: Subtract axis=0 mean to normalize columns [OK]

Common Mistakes:

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