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Which axis does np.concatenate() join arrays along by default if not specified?

easy📝 Conceptual Q2 of 15
NumPy - Array Manipulation
Which axis does np.concatenate() join arrays along by default if not specified?
AAxis 0 (rows)
BAxis 1 (columns)
CAxis -1 (last axis)
DNo axis, it flattens arrays
Step-by-Step Solution
Solution:

  1. Step 1: Recall default axis behavior

    By default, np.concatenate() joins arrays along axis 0, which is the first dimension (rows for 2D arrays).

  2. Step 2: Understand axis parameter

    If axis is not given, it uses axis=0, so arrays stack vertically by default.

  3. Final Answer:

    Axis 0 (rows) -> Option A

  4. Quick Check:

    Default axis in np.concatenate() = 0 [OK]
Quick Trick: Default axis in concatenate is 0 (rows) [OK]
Common Mistakes:
  • Assuming default axis is 1 (columns)
  • Thinking it flattens arrays by default
  • Confusing axis numbering

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