Pivoting in Python

pivot turns a key column into columns, aggregating where keys repeat.

import polars as pl

frame = pl.DataFrame({
    "day": ["mon", "mon", "tue", "tue"],
    "lang": ["python", "rust", "python", "sql"],
    "tpm": [104, 98, 91, 79],
})

grid = frame.pivot(on="lang", index="day", values="tpm",
                   aggregate_function="mean")
print(grid)
print(grid.columns)

How it works

1. on names the column whose values become headers.
2. index is what stays as rows.
3. aggregate_function resolves collisions.

Keywords and builtins used here

• as
• print

The run, in numbers

Lines

12

Characters to type

271

Tokens

111

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 61 seconds.

Type this snippet

Step 3 of 5 in Reshaping & joining, step 17 of 32 in Polars.

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