From af86aea90dafcbf457e2f7d10dba5b5481e858d0 Mon Sep 17 00:00:00 2001
From: gyuton <40863448+gyuton@users.noreply.github.com>
Date: Mon, 25 Oct 2021 14:47:18 +0300
Subject: [PATCH] DOCSUP-10111: Documented the entropy aggregate function
 (#30237)

* initial commit

* Update draft

* small fix
---
 .../aggregate-functions/reference/entropy.md  | 43 +++++++++++++++++++
 .../aggregate-functions/reference/entropy.md  | 43 +++++++++++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 docs/en/sql-reference/aggregate-functions/reference/entropy.md
 create mode 100644 docs/ru/sql-reference/aggregate-functions/reference/entropy.md

diff --git a/docs/en/sql-reference/aggregate-functions/reference/entropy.md b/docs/en/sql-reference/aggregate-functions/reference/entropy.md
new file mode 100644
index 00000000000..5ebb678e6b5
--- /dev/null
+++ b/docs/en/sql-reference/aggregate-functions/reference/entropy.md
@@ -0,0 +1,43 @@
+---
+toc_priority: 302
+---
+
+# entropy {#entropy}
+
+Calculates [Shannon entropy](https://en.wikipedia.org/wiki/Entropy_(information_theory)) of a column of values.
+
+**Syntax**
+
+``` sql
+entropy(val)
+```
+
+**Arguments**
+
+-   `val` — Column of values of any type.
+
+**Returned value**
+
+-   Shannon entropy.
+
+Type: [Float64](../../../sql-reference/data-types/float.md).
+
+**Example**
+
+Query:
+
+``` sql
+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;
+```
+
+Result:
+
+``` text
+┌─entropy(vals)─┬─entropy(strings)─┐
+│             1 │             1.75 │
+└───────────────┴──────────────────┘
+```
diff --git a/docs/ru/sql-reference/aggregate-functions/reference/entropy.md b/docs/ru/sql-reference/aggregate-functions/reference/entropy.md
new file mode 100644
index 00000000000..b5abe00fd96
--- /dev/null
+++ b/docs/ru/sql-reference/aggregate-functions/reference/entropy.md
@@ -0,0 +1,43 @@
+---
+toc_priority: 302
+---
+
+# entropy {#entropy}
+
+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.
+
+**Синтаксис**
+
+``` sql
+entropy(val)
+```
+
+**Аргументы**
+
+-   `val` — столбец значений любого типа
+
+**Возвращаемое значение**
+
+-   Информационная энтропия.
+
+Тип: [Float64](../../../sql-reference/data-types/float.md).
+
+**Пример**
+
+Запрос:
+
+``` sql
+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;
+```
+
+Результат:
+
+``` text
+┌─entropy(vals)─┬─entropy(strings)─┐
+│             1 │             1.75 │
+└───────────────┴──────────────────┘
+```