From 774229e3f9eb2684218a21d5551f5d0d09974b4f Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Sat, 29 Jun 2019 10:29:43 +0800
Subject: [PATCH] add doc

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 docs/lib2-sort.md | 32 ++++++++++++++++++++++++++++++++
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 create mode 100644 docs/lib2-sort.md

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+# sort
+
+Sorts the elements of a list in ascending order. The list is a list-of-list construct, such as `[[a0, a1, a2...], [b0, b1, b2,...], [c0, c1, c2,...],...]`. When sorting, the function looks only at one index position of each sublist. 
+
+**Since: ** 2.0
+
+## Parameters
+
+- `lt` : The original list.
+- `by` : Can be `"x"`、`"y"`、`"z"`, or `"idx"` (Default).
+- `idx` : When `by` is `"idx"`, the value of `idx` is used. The Default value is 0.
+
+## Examples
+
+    include <util/sort.scad>;
+
+    assert(
+        [[2, 0, 0], [5, 0, 0], [7, 0, 0], [9, 0, 0], [10, 0, 0]] == 
+        sort([[10, 0, 0], [5, 0, 0], [7, 0, 0], [2, 0, 0], [9, 0, 0]])
+    );
+
+    assert(
+        [[2, 0, 0], [5, 0, 0], [7, 0, 0], [9, 0, 0], [10, 0, 0]] == 
+        sort([[10, 0, 0], [5, 0, 0], [7, 0, 0], [2, 0, 0], [9, 0, 0]], by = "x")
+    );
+
+    assert(
+        [[0, 2, 0], [0, 5, 0], [0, 7, 0], [0, 9, 0], [0, 10, 0]] == 
+        sort([[0, 10, 0], [0, 5, 0], [0, 7, 0], [0, 2, 0], [0, 9, 0]], by = "idx", idx = 1)
+    );
+
+