How to randomly shuffle a list
Tcl, 13 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 | proc K { x y } { set x }
proc shuffle4 { list } {
set n [llength $list]
while {$n > 0} {
set j [expr {int(rand()*$n)}]
lappend slist [lindex $list $j]
incr n -1
set temp [lindex $list $n]
set list [lreplace [K $list [set list {}]] $j $j $temp]
}
return $slist
}
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See also the Shuffle a list ( http://www.purl.org/thecliff/tcl/wiki/941.html ) page on the wiki for a performance comparison of several algorithms for doing this. The algorithm presented here is number 4 on that page (by Stephen Cohen).
Tags: datastructures
