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# sorting an associative array keys based on values

Hi
I have an associative array like this:
arr[x1]=30; arr[x2]=20;arr[x3]=40;arr[x4]=10;

I want the sort function to sort keys in ascending order of the values
on the right hand side with the following result:
x4,x2,x1,x3

Thank you

Jul 23 '05 #1
5 37227
so***********@yahoo.com wrote:
Hi
I have an associative array like this:
arr[x1]=30; arr[x2]=20;arr[x3]=40;arr[x4]=10;

I want the sort function to sort keys in ascending order of the values
on the right hand side with the following result:
x4,x2,x1,x3

Thank you

<script language="JavaScript">
// create an array
var arr = [];
arr["x1"]=30;
arr["x2"]=20;
arr["x3"]=40;
arr["x4"]=10;

// show the current array
for (var sKey in arr)
document.write(sKey + ':' + arr[sKey] + '; ');
document.write('<br />');

// sort 'array'
var arr2 = sortAssoc(arr);

// show the sorted array
for (var sKey in arr2)
document.write(sKey + ':' + arr2[sKey] + '; ');
document.write('<br />');

// And here comes the funciton itself
function sortAssoc(aInput)
{
var aTemp = [];
for (var sKey in aInput)
aTemp.push([sKey, aInput[sKey]]);
aTemp.sort(function () {return arguments[0][1] < arguments[1][1]});

var aOutput = [];
for (var nIndex = aTemp.length-1; nIndex >=0; nIndex--)
aOutput[aTemp[nIndex][0]] = aTemp[nIndex][1];

return aOutput;
}
</script>

Hope I helped you/
Sergey.

Jul 23 '05 #2
so***********@yahoo.com wrote:
Hi
I have an associative array like this:
arr[x1]=30; arr[x2]=20;arr[x3]=40;arr[x4]=10;

I want the sort function to sort keys in ascending order of the values
on the right hand side with the following result:
x4,x2,x1,x3

If you can guarantee unique numeric keys on the right...

function assocSort (oAssoc) {
var idx; var key; var arVal = []; var arValKey = []; var oRes = {};
for (key in oAssoc) {
arVal[arVal.length] = oAssoc[key];
arValKey[oAssoc[key]] = key;
}
arVal.sort();
for (idx in arVal)
oRes[arValKey[arVal[idx]]] = arVal[idx];
return oRes;
}

var arr = {x1:30, x2:20, x3:40, x4:10}
var arrSorted = assocSort(arr);
Csaba Gabor from Vienna

Jul 23 '05 #3
> I have an associative array
Thank you for your perfect language
;-) :-|
I want the sort function to sort keys
in ascending order of the values

(1) First of all, you may want to use the standard associative array
syntacs for predefined values (given that x1...x4 are real variables in

var map = { x1 : 30, x2 : 20 , x3 : 40, x4 : 10};

(2) JavaScript doesn't have an associative array as a programming
entity. So any more or less complicated operations over an associative
array have to be programmed manually by yourselve. In your case there
is no way (?) to accomplish that w/o multiple pass over the hash
table.
To be continued... (if you still need it)

Jul 23 '05 #4
so***********@yahoo.com writes:
I have an associative array like this:
arr[x1]=30; arr[x2]=20;arr[x3]=40;arr[x4]=10;
I guess you have
var arr = new Object();
or something, as well as the variables x1..x4 declared.
I want the sort function to sort keys in ascending order of the values
on the right hand side with the following result:
x4,x2,x1,x3
I assume values are always numbers. Otherwise a less trivial
comparison function is needed.

function sortByValue(keyArray, valueMap) {
return keyArray.sort(function(a,b){return valueMap[a]-valueMap[b];});
}

testing:

var arr = {foo: 30, bar: 20, baz:40, doh: 10};
var keyArray = ["foo","bar","baz","doh"]

There you go.
/L
--
Lasse Reichstein Nielsen - lr*@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'
Jul 23 '05 #5
Lasse Reichstein Nielsen wrote:
so***********@yahoo.com writes:

I have an associative array like this:
arr[x1]=30; arr[x2]=20;arr[x3]=40;arr[x4]=10;

I guess you have
var arr = new Object();
or something, as well as the variables x1..x4 declared.

I may have read it wrong but I read it as more like arr['x1'] where the
quotes were forgotten. If the sort is to be done by strings (if they are
indeed strings) then its a simple matter of .sort() and .reverse().

If the sort is based on the value of the variables, then you wouldn't
always get the order x4, x3, x2, x1 unless you grab the variable name
itself and create your own list and then sort and reverse it.

--
Randy
comp.lang.javascript FAQ - http://jibbering.com/faq & newsgroup weekly
Jul 23 '05 #6

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