Renaming duplicates in Javascript Array

Question

I'm looking for the most efficient way to rename (append-1, -2 etc.) a variable, if it already exists in a string.

So I'm keeping an array"

dupeCheck = [];

And as soon as I see that a variable:

var UID;

Is already in my dupeCheck array, I want to immediately append the value of UID with -1,

Also, I need to prevent a third duplicate becoming string-1-1, but rather string-2..

I saw this: Appending the count to duplicates in a javascript string array before, but It's nog exactly what I want...

Any smart ideas? I prefer jQuery..

/Edit:

For example:

var dupeUIDCheck = [];  

$.each(data[IDS].UIDs[keys], function(keys, val)
     {
     var currString = val;
     switch (key)
 {
      case "UID":

       UID = unquote(currString);

   //TODO:
   //Detect if multiple UIDs are loaded from a single source, and
   //rename them:

   dupeUIDCheck.push(UID); //Push current ID onto existing array

       //Check if ID exists
       ?
       //If exists rename value of currString, save it in currString
       newName = currSting;
      break;

      case "otherstuff":
           //Other vars to parse
      break;
     }

So when we get out of the "UID" case, I want to make sure it has a unique value

Can you describe the steps with a little more detail? UID is the count of how many duplicates do you have or is it the var value which you're checking against the dupeCheck's values? I don't know what you're trying to do. — Fabrício Matté
– Fabrício Matté, Commented May 17, 2012 at 21:48

soimon · Accepted Answer · 2012-05-17 22:13:30Z

7

You can wrap the functionality in a function to be able to reuse it. The function below takes a list of strings and returns the -1, -2 etc. suffixed list of strings.

function suffixDuplicates( list )
{
    // Containers

    var count = { };
    var firstOccurences = { };

    // Loop through the list

    var item, itemCount;
    for( var i = 0, c = list.length; i < c; i ++ )
    {
        item = list[ i ];
        itemCount = count[ item ];
        itemCount = count[ item ] = ( itemCount == null ? 1 : itemCount + 1 );

        if( itemCount == 2 )
            list[ firstOccurences[ item ] ] = list[ firstOccurences[ item ] ] + "-1";
        if( count[ item ] > 1 )
            list[ i ] = list[ i ] + "-" + count[ item ]
        else
            firstOccurences[ item ] = i;       
    }

    // Return
    return list;
}

For example, an input of

[ "Barry", "Henk", "Jaap", "Peter", "Jaap", "Jaap", "Peter", "Henk", "Adam" ]

returns an output of

[ "Barry", "Henk-1", "Jaap-1", "Peter-1", "Jaap-2", "Jaap-3", "Peter-2", "Henk-2", "Adam" ]

To see it in action, here is a link to a jsFiddle example.

edited May 17, 2012 at 22:13

answered May 17, 2012 at 22:04

soimon

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1 Comment

TrySpace Over a year ago

This is about what I want, however, I don't want to return a list/array, but just the renamed value, so the list/array is only to keep track of dupes

Sampson · Accepted Answer · 2012-05-17 22:49:32Z

2

It's a little difficult to understand your question, but please let me know if this is what you were referring to. Suppose we have a string of words, and some of the words repeat. We want to modify those repeated words with a new suffix, such as -1 or -2, depending which instance it is.

// Start by creating our string, word array, and result array
var string = "one two one one two one three three one three",
    values = string.split(" "), result = [];

// For every word in the values array
for ( var i = 0; i < values.length; i++ ) {

  // Set a word variable, and an integer suffix
  var word = values[i], int = 1;

  // While our current word (with/without suffix) exists in results
  while ( strArr(word, result) >= 0 ) 
    // Increment the suffix on our word
    word = values[i] + "-" + int++;

  // Push word into result array
  result.push(word);
}

// Function for determining if a string is in an array
function strArr(s,a){
  for ( var j = 0; j < a.length; j++ )
    if ( a[ j ] == s ) return j;
  return -1;
}

// Compare the before and after
console.log( string );
console.log( result.join(" ") );

Our result is

one two one one two one three three one three
one two one-1 one-2 two-1 one-3 three three-1 one-4 three-2

edited May 17, 2012 at 22:49

answered May 17, 2012 at 21:59

Sampson

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1 Comment

theHussle Over a year ago

A really nice clear answer, I actually optimized this slightly, by switching your strArr function with a .includes() check on the array. I'm sure you could easily take it even further.

jfriend00 · Accepted Answer · 2012-05-17 22:04:31Z

1

The best way to keep a list of things you're checking for dups on is to have them in an object, not an array so you can look them up quickly and then generate a unique suffix that isn't already in use each time. This function allows you to pass an id into the function and have the function return a unique version of that id that isn't already in use. If what was passed in was not in use, it just returns that. If what was passed in was in use, it strips any suffix off and generates a new suffix that isn't already in use and returns the newly minted id. The newly minted id is then stored in the data structure so it won't be duplicated in the future too.

var idList = {};

makeIdUnique(id) {
    if (id in idList) {
        // remove any existing suffix
        var base = id.replace(/-\d+$/, "");
        // generate a new suffix
        var cnt = idList[base] || 1;
        // while new suffix is in the list, keep making a different suffix
        do {
            id = base + "-" + cnt++;
        } while (id in idList);
        // save cnt for more efficient generation next time
        idList[base] = cnt;
    }
    // put the final id in the list so it won't get used again in the future
    idList[id] = true;
    // return the newly generated unique id
    return(id);
}

edited May 17, 2012 at 22:04

answered May 17, 2012 at 21:58

jfriend00

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3 Comments

TrySpace Over a year ago

That didn't do it really, stackoverflow.com/questions/10962412/…, and, modified it still leaves dupes: jsfiddle.net/HB7ev/13

jfriend00 Over a year ago

@TrySpace - you took out this line var base = id.replace(/-\d+$/, ""); which is an important part of my algorithm because it removes the passed in suffix to get the root so it can make a unique cnt using that root.

jfriend00 Over a year ago

@TrySpace - you changed the code and changed its behavior. For example, you made dupeUIDCheck into an array and I had idList as an object. I also don't understand what you think doesn't work in your example. Perhaps you need to restate your objective. And, it's a bit difficult to keep the context current when you wait multiple weeks between responses.

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