polars.internals.expr.list.ExprListNameSpace.first#

ExprListNameSpace.first() Expr[source]#

Get the first value of the sublists.

Examples

>>> df = pl.DataFrame({"foo": [[3, 2, 1], [], [1, 2]]})
>>> df.select(pl.col("foo").arr.first())
shape: (3, 1)
┌──────┐
│ foo  │
│ ---  │
│ i64  │
╞══════╡
│ 3    │
├╌╌╌╌╌╌┤
│ null │
├╌╌╌╌╌╌┤
│ 1    │
└──────┘