Question

I have two ArrayCollection and I want to merge them into one…

arr1 = 
[0] -> month = 07
       tot_err = 15
[1] -> month = 08
       tot_err = 16
[2] -> month = 09
       tot_err = 17


arr2 = 
[0] -> month = 07
       tot_ok = 5
[1] -> month = 08
       tot_ok = 6
[2] -> month = 09
       tot_ok = 7

I would like to have this array

arr3 = 
[0] -> month = 07
       tot_err = 15
       tot_ok = 5
[1] -> month = 08
       tot_err = 16
       tot_ok = 6
[2] -> month = 09
       tot_err = 17
       tot_ok = 7    

How can I do it?

EDIT:

I did this solution:

        private function mergeArrays(a:ArrayCollection, b:ArrayCollection):ArrayCollection
        {
            for (var i:int=0;i<a.length;i++)
                for each(var item:Object in b)
                {                   
                    if( a[i].month == item.month){
                         a[i].tot_err = item.tot_err;
                    }
                }
            return a;
        }

But there is an important problem, if array2 (b) has a item.month that there isn’t in the array1 (a) the value is lost…

Answer 1

private function mergeArrays(a:ArrayCollection, b:ArrayCollection):ArrayCollection
{
    var result:ArrayCollection = new ArrayCollection();
    var months:Dictionary = new Dictionary();
    for (var i:int = 0; i < a.length; i++)
    {
        var mergedItem:Object = new Object();
        mergedItem.month = a[i].month;
        mergedItem.tot_ok = a[i].tot_ok;
        mergedItem.tot_err = null;
        for (var j:int = 0; j < b.length; j++)
        {                   
            if(a[i].month == b[j].month)
            {
                mergedItem.tot_err = b[j].tot_err;
            }
        }
        month[mergedItem.month] = true;
        result.addItem(mergedItem);
    }
    // so far we have handled all occurrences between a and b,
    // now we need to handle the items from b that are left
    for each (var bItem:Object in b)
    {
        mergedItem = new Object();
        mergedItem.month = bItem.month;
        mergedItem.tot_err = bItem.tot_err;
        mergedItem.tot_ok = null;
        if (months[mergedItem.month] == null)
        {
            month[mergedItem.month] = true;
            result.addItem(mergedItem);
        }
    }
    return result;
}