PERF: series.map(arg) for category is slow if arg is a dict (original) (raw)

Are the following 2 methods equivalent? I have to introduce a lambda to gain additional performance when dealing with map of category.

import pandas as pd x = pd.Series(list('abcd') * 1000).astype('category') mapper = {'a': 1, 'b': 2, 'c': 3, 'd': 4} %timeit x.map(mapper)

1000 loops, best of 3: 1.11 ms per loop

%timeit x.map(lambda a: mapper[a])

1000 loops, best of 3: 291 µs per loop