polars.Expr.rle

Expr.rle() → Self

Compress the column data using run-length encoding.

Run-length encoding (RLE) encodes data by storing each run of identical values as a single value and its length.

Returns:

Expr

Expression of data type Struct with fields len of data type UInt32 and value of the original data type.

See also

rle_id

Examples

>>> df = pl.DataFrame({"a": [1, 1, 2, 1, None, 1, 3, 3]})
>>> df.select(pl.col("a").rle()).unnest("a")
shape: (6, 2)
┌─────┬───────┐
│ len ┆ value │
│ --- ┆ ---   │
│ u32 ┆ i64   │
╞═════╪═══════╡
│ 2   ┆ 1     │
│ 1   ┆ 2     │
│ 1   ┆ 1     │
│ 1   ┆ null  │
│ 1   ┆ 1     │
│ 2   ┆ 3     │
└─────┴───────┘