NumPy - Broadcasting
Which numpy code snippet correctly adds a 1D array to each row of a 2D array using broadcasting?
Which numpy code snippet correctly adds a 1D array to each row of a 2D array using broadcasting?
easy📝 Syntax Q3 of 15
Step-by-Step Solution
Solution:
Step 1: Understand shapes involved
The 2D array has shape (2,2). The 1D array with shape (2,) can broadcast across rows.Step 2: Check each option's shape compatibility
np.array([[1,2],[3,4]]) + np.array([1,2]) adds (2,2) + (2,) which broadcasts correctly. np.array([[1,2],[3,4]]) + np.array([[1,2]]) is (2,2) + (1,2) also works but is less common. np.array([[1,2],[3,4]]) + np.array([[1],[2]]) shape (2,1) adds column-wise. np.array([[1,2],[3,4]]) + np.array([1,2,3]) shape (3,) incompatible.Final Answer:
np.array([[1,2],[3,4]]) + np.array([1,2]) -> Option AQuick Check:
Adding 1D array to 2D rows = np.array([[1,2],[3,4]]) + np.array([1,2]) [OK]
Quick Trick: 1D array shape matches columns to add to rows [OK]
Common Mistakes:
- Using incompatible shapes causing errors
- Confusing row-wise and column-wise addition
- Adding arrays with different lengths
Master "Broadcasting" in NumPy
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