PERF: groupby(...).len by rhshadrach · Pull Request #57595 · pandas-dev/pandas (original) (raw)

size = 100_000
df = pd.DataFrame(
    {
        "a": np.random.randint(0, 100, size),
        "b": np.random.randint(0, 100, size),
    }
)
%timeit len(df.groupby(["a", "b"]))

# 161 ms ± 962 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)    <-- main
# 4.96 ms ± 229 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)  <-- PR