Compute entropy

Description

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

<Expr>$entropy(base = exp(1), ..., normalize = TRUE)

base Numeric value used as base, defaults to exp(1).

… These dots are for future extensions and must be empty.

normalize Normalize pk if it doesn’t sum to 1.

A polars expression

library("polars")

df <- pl$DataFrame(a = 1:3)
df$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 │
#> └───────────┘