Selection Sort

Code snippet for sorting an array/slice of comparable values of the same type in-place, using the selection sort algorithm.

Licensed under the terms of the Unlicense.

danger

Though this works fine for small slices/array, due to the inefficient nature of selection sort, running it on "large" slices/arrays (over 200-300 elements) will result in a runtime error. If you want to use this snippet, be careful and constrain your input sizes.

Code

{{/*
	Sorts an array/slice of numbers descending or ascending in place.
	See <https://yagpdb-cc.github.io/code-snippets/selection-sort> for more information.

	Licensed under the terms of the Unlicense.
	Author: jo3-l <https://github.com/jo3-l>
*/}}

{{/* Let $arr be the array/slice to sort. */}}
{{ $arr := cslice 1 38 -1 83 -4 5 1 0 }}

{{ $len := len $arr }}
{{ range seq 0 $len }}
	{{- $min := . }}
	{{- range seq (add . 1) $len }}
		{{- if lt (index $arr $min) (index $arr .) }} {{- $min = . }} {{- end -}}
	{{- end }}
	{{- if ne $min . }}
		{{- $ := index $arr . }}
		{{- $arr.Set . (index $arr $min) }}
		{{- $arr.Set $min $ }}
	{{- end -}}
{{ end }}

Usage

First, add the code snippet above:

{{/* code snippet goes here */}}

Next, change the value of $arr to the value you want to sort:

{{/* Let $arr be the array/slice to sort. */}}
- {{ $arr := cslice 1 38 -1 83 -4 5 1 0 }}
+ {{ $arr := theSliceIWantToSort }}
{{/* rest of code snippet goes here */}}

Voila, $arr is now sorted! You can check that it was by outputting $arr:

{{/* code snippet goes here */}}
`$arr` after sorting: `{{json $arr}}`

Sorting in ascending order

You may have noticed that the above snippet sorts the array in descending order by default - larger numbers come first. That may not be desirable for your use case; perhaps you want smaller numbers to come first. In that case, you just have to change lt to gt in the following part of the code:

{{/* rest of code snippet */}}
{{- range seq (add . 1) $len }}
-   {{- if lt (index $arr $min) (index $arr .) }} {{- $min = . }} {{- end -}}
+   {{- if gt (index $arr $min) (index $arr .) }} {{- $min = . }} {{- end -}}
{{- end }}
{{/* rest of code snippet */}}

Author

This code snippet was written by @jo3-l.