ruff/docs/rules/use-of-inplace-argument.md

use-of-inplace-argument (PD002)

Derived from the pandas-vet linter.

Autofix is always available.

What it does

Checks for inplace=True usages in pandas function and method calls.

Why is this bad?

Using inplace=True encourages mutation rather than immutable data, which is harder to reason about and may cause bugs. It also removes the ability to use the method chaining style for pandas operations.

Further, in many cases, inplace=True does not provide a performance benefit, as pandas will often copy DataFrames in the background.

Example

df.sort_values("col1", inplace=True)

Use instead:

sorted_df = df.sort_values("col1")

References

• Why You Should Probably Never Use pandas inplace=True