Sort stability: Difference between revisions

Content added Content deleted
(adding gap, but not sure !)
(→‎{{header|GAP}}: more readable I hope)
Line 83:
 
=={{header|GAP}}==
<lang gap># According to section 21.18 of the reference manual, Sort is not stable. However,(it's a Shell sort).
# However, SortingPerm is stable. We will see it on an example, showing indexes of elements after the sort.
s:=List([1 .. 40], n -> Random("AB"));▼
# "BBBABBBAABBBAAAABBAABBAAABBABBABABABABAB"
 
n := 20;
p:=SortingPerm(s);▼
▲sL := List([1 .. 40n], ni -> Random("AB"));
# (1,19,8,2,20,9,3,21,30,35,16,7,24,11,26,32,36,38,39,18,29,34,37,17,28,13,4)(5,22,31,14)(6,23,10,25,12,
# "AABABBBABBABAABABBAB"
# 27,33,15)
 
Permuted([1 .. 40], p);▼
# [ 4, 8, 9, 13, 14, 15, 16, 19, 20, 23, 24, 25, 28, 31, 33, 35, 37, 39, 1, 2, 3, 5, 6, 7, 10, 11, 12,
# 17, 18, 21, 22, 26, 27, 29, 30, 32, 34, 36, 38, 40 ]
 
▲p := SortingPerm(sL);
# So it looks like the sorting algorithm used is indeed stable. It may be useful to investigate GAP source code.</lang>
# (3,10,15,17,18,19,9,14,7,13,6,12,16,8,4)(5,11)
 
a := Permuted(L, p);;
▲b := Permuted([1 .. 40n], p);;
 
PrintArray(TransposedMat(List([1 .. n], i -> [a[i], b[i]])));
# [ [ 'A', 'A', 'A', 'A', 'A', 'A', 'A', 'A', 'A', 'B', 'B', 'B', 'B', 'B', 'B', 'B', 'B', 'B', 'B', 'B' ],
# [ 1, 2, 4, 8, 11, 13, 14, 16, 19, 3, 5, 6, 7, 9, 10, 12, 15, 17, 18, 20 ] ]</lang>
 
=={{header|Go}}==
Retrieved from "https://rosettacode.org/wiki/Sort_stability"