The result of filtering df with Expr.str.starts_with changes depending on the suffix.

[NMZ0429]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

import polars as pl

df = pl.DataFrame({
    "x": ["CS00621400001"]
})
print(df)

filtered_df = df.filter(pl.col("x").str.starts_with("C"))
print(filtered_df) # NOTE: no row is printed

df = pl.DataFrame({
    "x": ["CS0062140000"]
})
print(df)

filtered_df = df.filter(pl.col("x").str.starts_with("C"))
print(filtered_df) # NOTE: one row is printed

Log output

No response

Issue description

Given a dataframe with the value CS00621400001, filtering it with str.starts_with("C") does not catch the row. However, removing the trailing 1 of the value i.e., the value CS0062140000 changes the result of the filtering and the row is caught.

Expected behavior

Both CS00621400001 and CS0062140000 are caught by the filter condition str.starts_with("C") .

Installed versions

--------Version info---------
Polars:              1.15.0
Index type:          UInt32
Platform:            macOS-14.6.1-arm64-arm-64bit
Python:              3.12.7 | packaged by conda-forge | (main, Oct  4 2024, 15:57:01) [Clang 17.0.6 ]
LTS CPU:             False

----Optional dependencies----
adbc_driver_manager  <not installed>
altair               <not installed>
boto3                <not installed>
cloudpickle          <not installed>
connectorx           <not installed>
deltalake            <not installed>
fastexcel            <not installed>
fsspec               <not installed>
gevent               <not installed>
google.auth          <not installed>
great_tables         <not installed>
matplotlib           3.9.2
nest_asyncio         1.6.0
numpy                2.1.3
openpyxl             <not installed>
pandas               
2.2.3
pyarrow              18.0.0
pydantic             <not installed>
pyiceberg            <not installed>
sqlalchemy           <not installed>
torch                <not installed>
xlsx2csv             <not installed>
xlsxwriter           <not installed>

[cmdlineluser]

I believe this is fixed on main: #20003

[alexander-beedie]

Yup, this was fixed by #20006; I believe the 1.16 release will be coming shortly and that contains this patch.