Log Message:
-----------
added fisher_yates_shuffle() inplace-randomization routine.
Modified Files:
--------------
webwork2/lib/WeBWorK:
Utils.pm
Revision Data
-------------
Index: Utils.pm
===================================================================
RCS file: /webwork/cvs/system/webwork2/lib/WeBWorK/Utils.pm,v
retrieving revision 1.59
retrieving revision 1.60
diff -Llib/WeBWorK/Utils.pm -Llib/WeBWorK/Utils.pm -u -r1.59 -r1.60
--- lib/WeBWorK/Utils.pm
+++ lib/WeBWorK/Utils.pm
@@ -74,6 +74,7 @@
cryptPassword
dequote
undefstr
+ fisher_yates_shuffle
sortByName
);
@@ -721,6 +722,18 @@
sub undefstr($@) {
map { defined $_ ? $_ : $_[0] } @_[1..$#_];
+}
+
+# shuffle an array in place
+# Perl Cookbook, Recipe 4.17. Randomizing an Array
+sub fisher_yates_shuffle {
+ my $array = shift;
+ my $i;
+ for ($i = @$array; --$i; ) {
+ my $j = int rand ($i+1);
+ next if $i == $j;
+ @$array[$i,$j] = @$array[$j,$i];
+ }
}
################################################################################
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