polars.Expr.bin.starts_with#
- Expr.bin.starts_with(prefix: IntoExpr) Expr [source]#
Check if values start with a binary substring.
- Parameters:
- prefix
Prefix substring.
- Returns:
- Expr
Expression of data type
Boolean
.
See also
Examples
>>> colors = pl.DataFrame( ... { ... "name": ["black", "yellow", "blue"], ... "code": [b"\x00\x00\x00", b"\xff\xff\x00", b"\x00\x00\xff"], ... "prefix": [b"\x00", b"\xff\x00", b"\x00\x00"], ... } ... ) >>> colors.select( ... "name", ... pl.col("code").bin.starts_with(b"\xff").alias("starts_with_lit"), ... pl.col("code") ... .bin.starts_with(pl.col("prefix")) ... .alias("starts_with_expr"), ... ) shape: (3, 3) ┌────────┬─────────────────┬──────────────────┐ │ name ┆ starts_with_lit ┆ starts_with_expr │ │ --- ┆ --- ┆ --- │ │ str ┆ bool ┆ bool │ ╞════════╪═════════════════╪══════════════════╡ │ black ┆ false ┆ true │ │ yellow ┆ true ┆ false │ │ blue ┆ false ┆ true │ └────────┴─────────────────┴──────────────────┘