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45 lines
1.2 KiB
Markdown
45 lines
1.2 KiB
Markdown
---
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slug: /ru/sql-reference/aggregate-functions/reference/entropy
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sidebar_position: 302
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---
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# entropy {#entropy}
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Вычисляет [информационную энтропию](https://ru.wikipedia.org/wiki/%D0%98%D0%BD%D1%84%D0%BE%D1%80%D0%BC%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%BD%D0%B0%D1%8F_%D1%8D%D0%BD%D1%82%D1%80%D0%BE%D0%BF%D0%B8%D1%8F) столбца данных.
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**Синтаксис**
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``` sql
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entropy(val)
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```
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**Аргументы**
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- `val` — столбец значений любого типа
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**Возвращаемое значение**
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- Информационная энтропия.
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Тип: [Float64](../../../sql-reference/data-types/float.md).
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**Пример**
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Запрос:
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``` sql
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CREATE TABLE entropy (`vals` UInt32,`strings` String) ENGINE = Memory;
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INSERT INTO entropy VALUES (1, 'A'), (1, 'A'), (1,'A'), (1,'A'), (2,'B'), (2,'B'), (2,'C'), (2,'D');
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SELECT entropy(vals), entropy(strings) FROM entropy;
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```
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Результат:
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``` text
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┌─entropy(vals)─┬─entropy(strings)─┐
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│ 1 │ 1.75 │
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└───────────────┴──────────────────┘
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```
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