col.str.contains does not respect case insensitive regex object

[kymckay]

Have you tried latest version of polars?

• yes

What version of polars are you using?

0.8.0

What operating system are you using polars on?

Debian

What node version are you using

v18.13.0

Describe your bug.

Using the str.contains function of a column doesn't respect the case insensitive flag of a provided regex object.

What are the steps to reproduce the behavior?

Use str.contains on a column, providing a regex object created with the "i" flag for case insensitivity. Test it on a sample with different casing than the original regex pattern.

Example

import pl from "nodejs-polars"

let df = pl.DataFrame({
    "text": ["foo", "FOO", "FoO"],
})

const regex = new RegExp("foo", "i")

df = df.withColumn(pl.col("text").str.contains(regex).alias("result"))

console.log(df.toString())

What is the actual behavior?

The contains function does not match all case variations.

shape: (3, 2)
┌──────┬────────┐
│ text ┆ result │
│ ---  ┆ ---    │
│ str  ┆ bool   │
╞══════╪════════╡
│ foo  ┆ true   │
│ FOO  ┆ false  │
│ FoO  ┆ false  │
└──────┴────────┘

What is the expected behavior?

The contains function should match all variations. Probably by injecting the appropriate (?i) and (?-i) flags for polars to interpret.

shape: (3, 2)
┌──────┬────────┐
│ text ┆ result │
│ ---  ┆ ---    │
│ str  ┆ bool   │
╞══════╪════════╡
│ foo  ┆ true   │
│ FOO  ┆ true   │
│ FoO  ┆ true   │
└──────┴────────┘

[kymckay]

For what it's worth this is easily worked around using a string and the (?i), (?-i) flags as needed. I'm just raising for posterity.

[universalmind303]

closed via #92