Sorting algorithms/Radix sort

From Rosetta Code
Revision as of 03:53, 19 January 2011 by rosettacode>Lambertdw (Created page with "{{task|Sorting Algorithms}}{{Sorting Algorithm}} In this task, the goal is to sort an integer array with the radix sort algorithm. Primary purpose is to complete the characteriz...")
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Task
Sorting algorithms/Radix sort
You are encouraged to solve this task according to the task description, using any language you may know.

In this task, the goal is to sort an integer array with the radix sort algorithm. Primary purpose is to complete the characterization of sort algorithms task.

For more information see the detailed article on Wikipedia.

J

Generally, this task should be accomplished in J using /:~. Here we take an approach that's more comparable with the other examples on this page.

keys f/. data evaluates the function f on each group of data at the same position as similar keys. Sorting requires ordered keys. This code uses a J idiom: prepend the keys and matching data. The extra data is removed by behead }..

<lang j> NB. queue implementation of LSB radix sort. radixSort =: 3 : 0 NB. base radixSort data 16 radixSort y

keys =. x #.^:_1 y NB. compute keys length =. {:#{.keys extra =. (x,-length) {. ,. buckets =. i.x for_pass. 0{i.-length do.

 keys =. ,&:>/ (buckets,keys{~"1<pass) <@:}./.extra,keys
 extra =. 1 |. extra

end. x#.keys NB. restore the data ) </lang>

Sort 10 small numbers in base 3.

   (,: 3&radixSort) ?@#~10
1 3 8 9 0 0 8 7 1 6
0 0 1 1 3 6 7 8 8 9

Python

The wikipedia article cited in the introduction includes a python implementation of LSB radix sort.