polars.Expr.entropy

Expr.entropy(

base: float = 2.718281828459045,

*,

normalize: bool = True,

) → Expr

Computes the entropy.

Uses the formula -sum(pk * log(pk) where pk are discrete probabilities.

Parameters:

base

Given base, defaults to e

normalize

Normalize pk if it doesn’t sum to 1.

Examples

>>> df = pl.DataFrame({"a": [1, 2, 3]})
>>> df.select(pl.col("a").entropy(base=2))
shape: (1, 1)
┌──────────┐
│ a        │
│ ---      │
│ f64      │
╞══════════╡
│ 1.459148 │
└──────────┘
>>> df.select(pl.col("a").entropy(base=2, normalize=False))
shape: (1, 1)
┌───────────┐
│ a         │
│ ---       │
│ f64       │
╞═══════════╡
│ -6.754888 │
└───────────┘