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DeflateAwning/polars_upgrade_regex_magic.md

Last active February 21, 2025 00:51
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Polars Upgrade Regex Magic
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polars_upgrade_regex_magic.md

Sometimes the Python Polars library upgrades.

The following are some codebase migrations I've used.

Pre-v0.20.x

  1. Find+Replace: pl.Utf8 -> pl.String

v0.20.31 to v1.x

  1. Find+Replace how='outer_coalesce' on joins
Find:
how\s*=\s*['"]outer_coalesce['"]\s*,

Replace:
how='full', coalesce=True,
  1. Locate .replace(..., return_dtype=something)
rg -U -t py '\.replace\([^)]+return_dtype'
  1. Non-breaking change with infer_schema_length (from 0 to False to read all as String):
Find: infer_schema_length\s*=\s*0
Replace: infer_schema_length=False
  1. Find pl.read_csv, and pin engine='xlsx2csv' arg (or migrate manually).
  2. Find and Replace all .frame_equal( to .equals(.
  3. Note that df.drop(['column_that_does_not_exist']) now raises an exception.

v1.12 to v1.22

Not sure where in this range each of these broke/are required, but:

  1. \w+\.fill_null\((pl\.lit\()?0 -> df.with_columns(pl.selectors.numeric(pl.lit(0))
  • Note: Requires regex rework.
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