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Hi Anyone know how to randomize
- Thread starter nsampson1
- Start date
This will get random values from yuor list. The only problem being is that it will return duplicate enteries.
given a list: 1,2,3,4,5,6,7
this will return 3,3,7,6,6,4
but this is the basic way to get random values from a list!
<CFSET randList = "">
<CFLOOP INDEX="i" LIST="#bList#" DELIMITERS=",">
<CFSET randPos = RandRange(1,ListLen(bList))>
<CFSET randVal = ListGetAt(bList,randPos)>
<CFSET randList = ListAppend(randList,randVal)>
</CFLOOP>
hope this helps !
given a list: 1,2,3,4,5,6,7
this will return 3,3,7,6,6,4
but this is the basic way to get random values from a list!
<CFSET randList = "">
<CFLOOP INDEX="i" LIST="#bList#" DELIMITERS=",">
<CFSET randPos = RandRange(1,ListLen(bList))>
<CFSET randVal = ListGetAt(bList,randPos)>
<CFSET randList = ListAppend(randList,randVal)>
</CFLOOP>
hope this helps !
Guest
thanks for the suggestion arperry
sadly, I need to avoid duplicates in my random list - I could do this by using a conditional loop with <cfif> tags to make sure no duplicates appear. Something like:
<CFSET oldList = "1,2,3,4,5,6,7,8,9">
<CFSET newList = "">
<CFLOOP Condition = "ListLen(myList, ","
LT ListLen(oldList, ","">
<CFSET randPos = RandRange(1,ListLen(oldList, ",")>
<CFSET randVal = ListGetAt(oldList,randPos, ",">
<CFIF ListContains(newList, randVal, "," IS 0>
<CFSET newList = ListAppend(newList, randVal, ",">
</CFIF>
</CFLOOP>
This would probably do the trick but I'm concerned that it would slow down the page due to the uncertain length of the loop. I may have to go with this unless there are any more elegant ways of doing this
Neil
sadly, I need to avoid duplicates in my random list - I could do this by using a conditional loop with <cfif> tags to make sure no duplicates appear. Something like:
<CFSET oldList = "1,2,3,4,5,6,7,8,9">
<CFSET newList = "">
<CFLOOP Condition = "ListLen(myList, ","
LT ListLen(oldList, ",""><CFSET randPos = RandRange(1,ListLen(oldList, ","
)><CFSET randVal = ListGetAt(oldList,randPos, ","
><CFIF ListContains(newList, randVal, ","
IS 0><CFSET newList = ListAppend(newList, randVal, ","
></CFIF>
</CFLOOP>
This would probably do the trick but I'm concerned that it would slow down the page due to the uncertain length of the loop. I may have to go with this unless there are any more elegant ways of doing this
Neil
- Thread starter
- #4
Someone answered my question in another forum - just thought I would post the answer incase anyone finds it useful:
the trick is to delete the entry from the old list on each loop:
<cfset oldlist="1,2,4,7,9,12,22,31,35">
<cfset newlist="">
<cfset temp=randomize(gettickcount())>
<cfloop from="#listlen(oldlist)#" to="1" step="-1" index="i">
<cfset p=randrange(1,i)>
<cfset newlist=listappend(newlist,listgetat(oldlist,p))>
<cfset oldlist=listdeleteat(oldlist,p)>
</cfloop>
<cfoutput>#newlist#</cfoutput>
the trick is to delete the entry from the old list on each loop:
<cfset oldlist="1,2,4,7,9,12,22,31,35">
<cfset newlist="">
<cfset temp=randomize(gettickcount())>
<cfloop from="#listlen(oldlist)#" to="1" step="-1" index="i">
<cfset p=randrange(1,i)>
<cfset newlist=listappend(newlist,listgetat(oldlist,p))>
<cfset oldlist=listdeleteat(oldlist,p)>
</cfloop>
<cfoutput>#newlist#</cfoutput>
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