Function field

python/pyarrow/compute.py:690–736

Reference a column of the dataset. Stores only the field's name. Type and other information is known only when the expression is bound to a dataset having an explicit scheme. Nested references are allowed by passing multiple names or a tuple of names. For example ``('foo', 'bar')``

(*name_or_index)

def field(*name_or_index):
    """Reference a column of the dataset.

    Stores only the field's name. Type and other information is known only when
    the expression is bound to a dataset having an explicit scheme.

    Nested references are allowed by passing multiple names or a tuple of
    names. For example ``('foo', 'bar')`` references the field named "bar"
    inside the field named "foo".

    Parameters
    ----------
    *name_or_index : string, multiple strings, tuple or int
        The name or index of the (possibly nested) field the expression
        references to.

    Returns
    -------
    field_expr : Expression
        Reference to the given field

    Examples
    --------
    >>> import pyarrow.compute as pc
    >>> pc.field("a")
    <pyarrow.compute.Expression a>
    >>> pc.field(1)
    <pyarrow.compute.Expression FieldPath(1)>
    >>> pc.field(("a", "b"))
    <pyarrow.compute.Expression FieldRef.Nested(FieldRef.Name(a) ...
    >>> pc.field("a", "b")
    <pyarrow.compute.Expression FieldRef.Nested(FieldRef.Name(a) ...
    """
    n = len(name_or_index)
    if n == 1:
        if isinstance(name_or_index[0], (str, int)):
            return Expression._field(name_or_index[0])
        elif isinstance(name_or_index[0], tuple):
            return Expression._nested_field(name_or_index[0])
        else:
            raise TypeError(
                "field reference should be str, multiple str, tuple or "
                f"integer, got {type(name_or_index[0])}"
            )
    # In case of multiple strings not supplied in a tuple
    else:
        return Expression._nested_field(name_or_index)


def scalar(value):