From ea3942210c838d7a1e9206445ad490b0240a55dc Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Mon, 8 Jan 2018 16:58:23 +0200
Subject: [PATCH] Add partition

---
 snippets/partition.md | 19 +++++++++++++++++++
 tag_database          |  1 +
 2 files changed, 20 insertions(+)
 create mode 100644 snippets/partition.md

diff --git a/snippets/partition.md b/snippets/partition.md
new file mode 100644
index 000000000..872308aae
--- /dev/null
+++ b/snippets/partition.md
@@ -0,0 +1,19 @@
+### partition
+
+Groups the elements into two arrays, depending on the provided function's truthiness for each element.
+
+Use `Array.reduce()` to create an array of two arrays.
+Use `Array.push()` to add elements for which `fn` returns `true` to the first array and elements for which `fn` returns `false` to the second one.
+
+```js
+const partition = (arr, fn) =>
+  arr.reduce((acc, val, i, arr) => {fn(val,i,arr) ? acc[0].push(val) : acc[1].push(val); return acc;},[[],[]]);
+```
+
+```js
+var users = [
+  { 'user': 'barney',  'age': 36, 'active': false },
+  { 'user': 'fred',    'age': 40, 'active': true }
+];
+partition(users, o => o.active) // [[{ 'user': 'fred',    'age': 40, 'active': true }],[{ 'user': 'barney',  'age': 36, 'active': false }]]
+```
diff --git a/tag_database b/tag_database
index a9862093d..c581d0f0f 100644
--- a/tag_database
+++ b/tag_database
@@ -111,6 +111,7 @@ once:function
 onUserInputChange:browser,event,advanced
 orderBy:object,array
 palindrome:string
+partition:array,object,function
 percentile:math
 pick:array
 pipeFunctions:adapter,function