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> Use this file to discover all available pages before exploring further.

> Calcule l’entropie de Shannon d’une colonne de valeurs.

# entropy

<div id="entropy">
  ## entropy
</div>

Disponible à partir de : v20.1.0

Calcule l’[entropie de Shannon](https://en.wikipedia.org/wiki/Entropy_\(information_theory\)) d’une colonne de valeurs.

**Syntaxe**

```sql theme={null}
entropy(val)
```

**Arguments**

* `val` — Colonne de valeurs de n’importe quel type. [`Any`](/fr/reference/data-types/index)

**Valeur renvoyée**

Renvoie l’entropie de Shannon. [`Float64`](/fr/reference/data-types/float)

**Exemples**

**Calcul basique de l’entropie**

```sql title=Query theme={null}
CREATE TABLE entropy (`vals` UInt32,`strings` String)
ENGINE = Memory;

INSERT INTO entropy VALUES (1, 'A'), (1, 'A'), (1,'A'), (1,'A'), (2,'B'), (2,'B'), (2,'C'), (2,'D');

SELECT entropy(vals), entropy(strings) FROM entropy
```

```response title=Response theme={null}
┌─entropy(vals)─┬─entropy(strings)─┐
│             1 │             1.75 │
└───────────────┴──────────────────┘
```