[thelist] CF: De-duplicating Arrays

Buffington, Michael michael.buffington at office.xerox.com
Tue Jul 15 07:52:35 CDT 2003


I threw something together real quick and dirty after reading your email that does the job using just arrays. No list conversion or anything. It runs pretty quick, although I haven't compared it to doing arrays to lists then back to arrays again.

Here's a question though: which of the two dupes do you keep if the values in the second dimension are different? My functions below keep the first occurrence of a dupe, and prevent the second from being set to the array. Also, the code only works for 2D arrays here, but could very easily be used for a single dimension. Also, the code for the ArrayFind function is not my own, although I modded it some. I lost track of who did it, but I use it quite often, it's quite handy.

Hope it helps.

myArr = ArrayNew(2);
myArr[1][1] = "Apples";
myArr[1][2] = "Macintosh";

myArr[2][1] = "Pears";
myArr[2][2] = "Green";

myArr[3][1] = "Oranges";
myArr[3][2] = "Mandarin";

myArr[4][1] = "Pears";
myArr[4][2] = "Japanese";

function ArrayFind(arrayToSearch,valueToFind,dimension){
	//a variable for looping
	var ii = 0;
	//loop through the array, looking for the value
	for(ii = 1; ii LTE arrayLen(arrayToSearch); ii = ii + 1){
		//if this is the value, return the index
		if(NOT compare(arrayToSearch[ii][dimension],valueToFind))
			return ii;
	//if we've gotten this far, it means the value was not found, so return 0
	return 0;

function arrayDeDupe(arrayToDeDupe,dimension) {

	// this could be smarter, detecting total dimensions
	arrySansDupe = arrayNew(2);
	indexCount = 1;
	// loop over the supplied array
	for (i=1;i lte ArrayLen(arrayToDeDupe);i=i+1) {		
		// populate cells only if they don't already exist
		if (ArrayFind(arrySansDupe,arrayToDeDupe[i][dimension],dimension) eq 0) {
			arrySansDupe[indexCount][dimension] = arrayToDeDupe[i][dimension];
			arrySansDupe[indexCount][dimension+1] = arrayToDeDupe[i][dimension+1];
			indexCount = indexCount + 1;
	return arrySansDupe;

newArry = arrayDeDupe(myArr,1);

-----Original Message-----
I'm trying  to  de-duplicate an a 2D array by it's first dimension. 

More information about the thelist mailing list