You have a 3D array A with shape (2, 3, 4) and a 1D array B with shape (4,). You want to add B to each 2D slice of A along the last axis. Which code correctly uses broadcasting to do this?

hard📝 Application Q15 of 15

NumPy - Broadcasting

You have a 3D array A with shape (2, 3, 4) and a 1D array B with shape (4,). You want to add B to each 2D slice of A along the last axis. Which code correctly uses broadcasting to do this?

A<code>C = A + B</code>

B<code>C = A + B.reshape(4, 1)</code>

C<code>C = A + B.reshape(1, 3)</code>

D<code>C = A + B.reshape(2, 3, 4)</code>

Step-by-Step Solution

Solution:

Step 1: Understand shapes and broadcasting rules
A shape is (2,3,4), B shape is (4,). Broadcasting aligns from the right, so B broadcasts along last axis of A.
Step 2: Evaluate each option's effect
C = A + B adds B directly, broadcasting B over last axis. C = A + B.reshape(4, 1) reshapes B to (4,1), incompatible with A's shape. C = A + B.reshape(1, 3) reshapes B to (1,3), which does not match A's last two dims. C = A + B.reshape(2, 3, 4) reshapes B to (2,3,4), but B has only 4 elements, so reshape fails.
Final Answer:
C = A + B -> Option A
Quick Check:
1D array matches last axis of 3D array [OK]

Quick Trick: Add 1D array matching last axis directly to 3D array [OK]

Common Mistakes:

Trying to reshape 1D array incorrectly
Assuming reshape is needed when broadcasting works
Confusing axis order in reshaping

Master "Broadcasting" in NumPy

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Visual Try Challenge Project Recall Time

Want More Practice?

15+ quiz questions · All difficulty levels · Free

Free Signup - Practice All Questions

More NumPy Quizzes

You have a 3D array A with shape (2, 3, 4) and a 1D array B with shape (4,). You want to add B to each 2D slice of A along the last axis. Which code correctly uses broadcasting to do this?

Step 1: Understand shapes and broadcasting rules

Step 2: Evaluate each option's effect

Final Answer:

Quick Check:

Want More Practice?