Given a 2D array matrix of shape (5, 1) and a 1D array vec of shape (5,), you want to add them element-wise. Which code correctly uses broadcasting to do this?

hard📝 Application Q9 of 15

NumPy - Broadcasting

Given a 2D array matrix of shape (5, 1) and a 1D array vec of shape (5,), you want to add them element-wise. Which code correctly uses broadcasting to do this?

Aresult = matrix + vec

Bresult = matrix.T + vec

Cresult = matrix + vec.reshape(5, 1)

Dresult = matrix + vec.reshape(1, 1)

Step-by-Step Solution

Solution:

Step 1: Check shapes of matrix and vec
matrix shape is (5,1), vec shape is (5,). NumPy pads the vec shape on the left with 1s to make it (1,5).
Step 2: Apply broadcasting
matrix broadcasts across columns, vec across rows, resulting in shape (5,5) matrix with element-wise sums.
Final Answer:
result = matrix + vec -> Option A
Quick Check:
Direct broadcasting (5,1) + (5,) -> (5,5) matrix [OK]

Quick Trick: (n,1) + (n,) broadcasts directly to (n,n) matrix [OK]

Common Mistakes:

Reshaping vec to (5,1) for column-wise sum
Transposing matrix to row vector first
Reshaping vec to (1,1) causing reshape error

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More NumPy Quizzes

Given a 2D array matrix of shape (5, 1) and a 1D array vec of shape (5,), you want to add them element-wise. Which code correctly uses broadcasting to do this?

Step 1: Check shapes of matrix and vec

Step 2: Apply broadcasting

Final Answer:

Quick Check:

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