Problem 2 of 3 · VectorizationNext: Bill tiered usage for every customer without a loop

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Practice / Python / Vectorization

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HardAbout 14 minVectorization

Vectorized size bands with NaN handling

Given an orders DataFrame with amount_usd (which may contain NaN), assign a size band without any Python loop, comprehension, or per-row function (apply, map, np.vectorize): - NaN → 'unknown' - < 50 → 'small' - < 200 → 'medium' - < 500 → 'large' - otherwise → 'whale'

Return the bands as a Python list, in row order.

What the tests check

2 on Run · 3 on Submit

01bands by amount with NaN -> unknown

02band boundaries are exclusive upper

Submit runs these and one more check you don’t see, so code written for the visible tests alone can still miss.

Runtime

Python 3.13 in your browser – the standard library plus pandas and numpy; no pip installs.

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