Actionscript 3 Count Number of Times a String Appears in an Array

Question

If I have an array similar to this:

var myArray:Array = new Array("a","b","c","d","e","f","g","b");

How can I search it to determine the number of times of value appears in it and in what positions? I found the code below which is close but it will only return the first occurrence.

function findIndexInArray(value:Object, arr:Array):Number {
    for (var i:uint=0; i < arr.length; i++) {
        if (arr[i]==value) {
            return i;
        }
    }
    return NaN;
}

var myArray:Array = new Array("a","b","c","d","e","f","g","b");
trace(findIndexInArray("b", myArray));

// OUTPUT
// 1

JeremyFromEarth · Accepted Answer · 2013-03-19 17:39:09Z

1

You might consider returning an Array of indicies where the search term exists. For example:

var list:Array = ['a', 'b', 'b', 'c', 'd', 'e', 'f'];

function find(obj:Object, list:Array):Array
{
    var result:Array = [];
    for(var i:int = 0; i < list.length; i++)
    {
        if(list[i] = obj)
        {
            result.push(i);
        }
    }
    return result;
 }

 var search:Array = find('b', list);
 trace('b is found: ' + search.length + ' times at indices: ' + search); 
 // -- 'b is found: 2 times at indices [1, 2]

This way you can see how many times the search term occurs by checking the length of the returned array.

answered Mar 19, 2013 at 17:39

JeremyFromEarth

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Comments

Daniel · Accepted Answer · 2013-03-20 15:56:28Z

0

you could use join and regex to do the count

something like this:

// convert to one long string
var str:String = myArray.join("");

// regex find the letter and count result
var count:int = str.match(new RegExp(letter,"a")).length;

haven't tested it, so the code might need a tweak, but this should be faster than looping through the array.

update

// convert to one long string
var str:String = myArray.join("");

var pos:Array = new Array();       
var n:int = -1;     

// loop through array and find all indexes
while ((n = str.indexOf(searchFor, n+1)) != -1) pos.push(n);

just a warning though, this will break if any string in the array has more than one character

edited Mar 20, 2013 at 15:56

answered Mar 19, 2013 at 17:51

Daniel

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2 Comments

JeremyFromEarth Over a year ago

Should this return where in the list the object occurs, or just the number of occurrences?

Daniel Over a year ago

oops, like I missed the position part, you can still use join and index, updating the post

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