ActionScript3 - add thousands separator to negative values - actionscript-3

Question

This question relates to an animated map template which we have developed at the UKs Office for National Statistics. It has been applied to many datasets and geographies many uses without problem. For example,
http://www.ons.gov.uk/ons/interactive/vp3-census-map/index.html
http://www.statistica.md/pageview.php?l=ro&idc=390&id=3807
The .fla calls on a supporting .as file (see below) to introduce a thousand separator (in the UK a comma, in Germany a full stop (period) defined elsewhwere.
However, the dataset I am currently mapping has large negative values, and it tutrns out that the ORIGINAL HELPER FUNCTION below does not like negative values with 3, 6, 9 or 12 (etc) digits.
-100 to -999 for instance are rendered NaN,100 to NaN,999.
This is because such values are recognised as being 4 digits long. They are being split, the comma introduced, and the -ve sign is misunderstood.
I reckon the approach must be to use absolute values, add in the comma and then (for the negative values) add the -ve sign back in afterwards. But so far, trials of the ADAPTED HELPER FUNCTION have produced only error. :-(
Can anyone tell me how to put the -ve sign back in , please?
Many thanks.
Bruce Mitchell
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//ORIGINAL HELPER FUNCTION: ACCEPTS A NUMBER AND RETURNS A STRING WITH THOUSANDS SEPARATOR ATTACHED IF NECESSARY
function addThouSep(num) {
/*
a. Acquire the number - 'myTrendValue' or 'myDataValue' - from function calcValues
b. Record it (still as a number) to data precision.
1. Turn dataORtrend into a string
2. See if there is a decimal in it.
3. If there isn't, just run the normal addThouSep.
4. If there is, run addThouSep just on the first bit of the string - then add the decimal back on again at the end.
*/
var myNum:Number = correctFPE(num); // Create number variable myNum and populate it with 'num'
// (myTrendvalue or myData Value from calcValues function) passed thru 'correctPFE'
var strNum:String = myNum+""; // Create string version of the dataORtrend number - so instead of 63, you get '63'
var myArray = strNum.split("."); // Create array representing elements of strNum, split by decimal point.
//trace(myArray.length); // How long is the array?
if (myArray.length==1) { // Integer, no decimal.
if (strNum.length < 4)//999 doesn't need a comma.
return strNum;
return addThouSep(strNum.slice(0, -3))+xmlData.thouSep+strNum.slice(-3);
}
else { // Float, with decimal
if (myArray[0].length < 4)//999 doesn't need a comma
return strNum;
return (addThouSep(myArray[0].slice(0, -3))+xmlData.thouSep+myArray[0].slice(-3)+"."+myArray[1]);
}
}
==================================================================================
//ADAPTED HELPER FUNCTION: ACCEPTS A NUMBER AND RETURNS A STRING WITH THOUSANDS SEPARATOR ATTACHED IF NECESSARY
function addThouSep(num) {
/*
a. Acquire the number - 'myTrendValue' or 'myDataValue' - from function calcValues
b. Record it (still as a number) to data precision.
1. Turn dataORtrend into a string
2. See if there is a decimal in it.
3. If there isn't, just run the normal addThouSep.
4. If there is, run addThouSep just on the first bit of the string - then add the decimal back on again at the end.
*/
var myNum:Number = correctFPE(num); // Create number variable myNum and populate it with 'num'
// (myTrendvalue or myData Value from calcValues function) passed thru 'correctPFE'
var myAbsNum:Number = Math.abs(myNum); // ABSOLUTE value of myNum
var strNum:String = myAbsNum+""; // Create string version of the dataORtrend number - so instead of 63, you get '63'
var myArray = strNum.split("."); // Create array representing elements of strNum, split by decimal point.
//trace(myArray.length); // How long is the array?
if (myNum <0){ // negatives
if (myArray.length==1) { // Integer, no decimal.
if (strNum.length < 4)//999 doesn't need a comma.
return strNum;
return addThouSep(strNum.slice(0, -3))+xmlData.thouSep+strNum.slice(-3);
}
else { // Float, with decimal
if (myArray[0].length < 4)//999 doesn't need a comma
return strNum;
return (addThouSep(myArray[0].slice(0, -3))+xmlData.thouSep+myArray[0].slice(-3)+"."+myArray[1]);
}
}
else // positive
if (myArray.length==1) { // Integer, no decimal.
if (strNum.length < 4)//999 doesn't need a comma.
return strNum;
return addThouSep(strNum.slice(0, -3))+xmlData.thouSep+strNum.slice(-3);
}
else { // Float, with decimal
if (myArray[0].length < 4)//999 doesn't need a comma
return strNum;
return (addThouSep(myArray[0].slice(0, -3))+xmlData.thouSep+myArray[0].slice(-3)+"."+myArray[1]);
}
}
==================================================================================

Answer 1

If you're adding commas often (or need to support numbers with decimals) then you may want a highly optimized utility function and go with straightforward string manipulation:
public static function commaify( input:Number ):String
{
var split:Array = input.toString().split( '.' ),
front:String = split[0],
back:String = ( split.length > 1 ) ? "." + split[1] : null,
pos:int = input < 0 ? 2 : 1,
commas:int = Math.floor( (front.length - pos) / 3 ),
i:int = 1;
for ( ; i <= commas; i++ )
{
pos = front.length - (3 * i + i - 1);
front = front.slice( 0, pos ) + "," + front.slice( pos );
}
if ( back )
return front + back;
else
return front;
}
While less elegant it's stable and performant — you can find a comparison suite at my answer of a similar question https://stackoverflow.com/a/13410560/934195

Answer 2

Why not use something simple like this function I've made?
function numberFormat(input:Number):String
{
var base:String = input.toString();
base = base.split("").reverse().join("");
base = base.replace(/\d{3}(?=\d)/g, "$&,");
return base.split("").reverse().join("");
}
Tests:
trace( numberFormat(-100) ); // -100
trace( numberFormat(5000) ); // 5,000
trace( numberFormat(-85600) ); // -85,600
Explanation:
Convert the input number to a string.
Reverse it.
Use .replace() to find all occurrences of three numbers followed by another number. We use $&, as the replacement, which basically means take all of those occurences and replace it with the value we found, plus a comma.
Reverse the string again and return it.

Answer 3

Did you try using the built in Number formatting options that support localized number values:
Localized Formatting with NumberFormatter