daft.functions.substr#

def substr(expr: Expression, start: int | Expression, length: int | Expression | None = None) -> Expression:
    """Extract a substring from a string, starting at a specified index and extending for a given length.

    Returns:
        Expression: A String expression representing the extracted substring.

    Note:
        If `length` is not provided, the substring will include all characters from `start` to the end of the string.

    Examples:
        >>> import daft
        >>> from daft.functions import substr
        >>> df = daft.from_pydict({"x": ["daft", "query", "engine"]})
        >>> df = df.select(substr(df["x"], 2, 4))
        >>> df.show()
        ╭────────╮
        │ x      │
        │ ---    │
        │ String │
        ╞════════╡
        │ ft     │
        ├╌╌╌╌╌╌╌╌┤
        │ ery    │
        ├╌╌╌╌╌╌╌╌┤
        │ gine   │
        ╰────────╯
        <BLANKLINE>
        (Showing first 3 of 3 rows)

    """
    return Expression._call_builtin_scalar_fn("substr", expr, start, length)