Question

I’ve created my own custom quicksort routine to work with a custom data structure I have. It should work just like a regular quicksort except that for comparisons I need use a special function to convert strings into numeric values.

Anyways I must have done something wrong because Firefox tells me “error too much recursion”.

Here is the code:

//Will be called on various buckets to sort by dates
function target_sort_wrapper(array) {
    target_sort(array, array.length, 0, length-1);
}

//Quicksort to swap around targets based on dates
//"array" is DDATA, where DDATA[i] are targets
function target_sort(array, length, left, right) {
    if (length < 2) return;
    var pivotIndex = choosePivot(array, length); //returns the index
    partition(array, pivotIndex, left, right);
    //recursive calls now - left then right
    target_sort(array, pivotIndex, 0, pivotIndex - 1);
    target_sort(array, array.length - (pivotIndex+1), pivotIndex+1, array.length - 1);
}

function partition(array, pivotIndex, left, right) {
    //first, put the pivot as the first element to make things easier
    swap(array, pivotIndex, 0);
    var pivot = array[0];
    var i = left + 1; 
    for(var j = left + 1; j < right; j++) {
        //if (array[j] > pivot) { } //do nothing, satisfies invariant
        if (dateValue(array[j].date) < dateValue(pivot.date)) {
            swap(array, i, j);
            i = i + 1; 
        }
    }
}

function choosePivot(array, length) {
    return Math.floor(Math.random() * length); //0 (inclusive) to length (exclusive) 
}

function swap(arr, i, j) {
    var temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
}

Thanks for any help.

Answer 1

To do a custom sort, you can use a “compare function”.
Take a look:

• How to sort this array with hashes?
• https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/sort

Although you have a good question, you don’t need to implement your sorting algorithm or be concerned about it, just use what I said.