def cov(
a: Union[str, "pl.Expr"],
b: Union[str, "pl.Expr"],
) -> "pl.Expr":
"""
Compute the covariance between two columns/ expressions.
Parameters
----------
a
Column name or Expression.
b
Column name or Expression.
"""
if isinstance(a, str):
a = col(a)
if isinstance(b, str):
b = col(b)
return pl.lazy.expr.wrap_expr(pycov(a._pyexpr, b._pyexpr))
def cov(
a: str | pli.Expr,
b: str | pli.Expr,
) -> pli.Expr:
"""
Compute the covariance between two columns/ expressions.
Parameters
----------
a
Column name or Expression.
b
Column name or Expression.
"""
if isinstance(a, str):
a = col(a)
if isinstance(b, str):
b = col(b)
return pli.wrap_expr(pycov(a._pyexpr, b._pyexpr))