Given a 2D numpy array arr = np.array([[1, 2], [3, 4], [5, 6]]), how would you select all elements greater than 3 using boolean indexing?

hard📝 Application Q8 of 15

NumPy - Indexing and Slicing

Given a 2D numpy array arr = np.array([[1, 2], [3, 4], [5, 6]]), how would you select all elements greater than 3 using boolean indexing?

Aarr[arr > 3]

Barr[:, arr > 3]

Carr[arr < 3]

Darr[3]

Step-by-Step Solution

Solution:

Step 1: Understand boolean indexing on 2D arrays
Boolean indexing flattens and selects elements matching condition.
Step 2: Apply condition arr > 3
arr[arr > 3] selects elements greater than 3: 4, 5, 6.
Final Answer:
arr[arr > 3] -> Option A
Quick Check:
Boolean indexing works element-wise on 2D arrays [OK]

Quick Trick: Boolean indexing flattens 2D arrays when filtering [OK]

Common Mistakes:

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