Powerful Polars is Terser with Tarsiers
Tarsiers is an add-on to Polars enabling more concise expressions and less typing. It is primarily intended for interactive use where quick iteration and concise code are most valuable.
More symbol-like columns, as it should be! For simply named columns
you can write C.foo instead of pl.col("foo").
Symbol-like symbols. Only N for now, but it's a nice feature from
data.table to borrow.
>>> import polars as pl
>>> import tarsiers as tr
>>> import tarsiers.col as C
>>> import tarsiers.symbols as S
>>> df = pl.DataFrame({"foo": [1, 3, 4], "bar": [3, 4, 0]})
>>> df.with_columns(
... tr.cases(C.foo > 2, 1, C.bar > 2, 4, default = -1).alias("val")
... )
shape: (3, 3)
┌─────┬─────┬─────┐
│ foo ┆ bar ┆ val │
│ --- ┆ --- ┆ --- │
│ i64 ┆ i64 ┆ i32 │
╞═════╪═════╪═════╡
│ 1 ┆ 3 ┆ 4 │
│ 3 ┆ 4 ┆ 1 │
│ 4 ┆ 0 ┆ 1 │
└─────┴─────┴─────┘
>>> df.groupby(C.foo % 2 == 1).agg(S.N, S.I, C.bar.sum())
shape: (2, 4)
┌───────┬───────┬───────────┬─────┐
│ foo ┆ count ┆ idx ┆ bar │
│ --- ┆ --- ┆ --- ┆ --- │
│ bool ┆ u32 ┆ list[u32] ┆ i64 │
╞═══════╪═══════╪═══════════╪═════╡
│ false ┆ 1 ┆ [2] ┆ 0 │
│ true ┆ 2 ┆ [0, 1] ┆ 7 │
└───────┴───────┴───────────┴─────┘