Removing Duplicate Strings Using Javascript

October 26, 2023 Post a Comment

I have an array of 800 sentences. I want to remove all duplicates (sentences that have the same exact words, but in different order) from the array. So for example 'this is a sente

Solution 1:

How about this?

va = ["this is a sentence", "sentence this is", "sentence this is a"]
vb = {} // dictionary of combined sorted words in each sentence
vc = [] // output list of sentences without duplicates for (i=0;i<va.length;i++){
    // split sentence, sort words, and recombine (this is a sentence => a is sentence this)var combined = va[i].split(" ").sort().join(" "); 

    if (!vb[combined]){       // if set of combined sorted words doesn't exist already
        vc.push(va[i]);      // sentence isn't duplicated, push to output list
        vb[combined] = true// add set to dictionary
    }
}

alert(vc.join("\n"))

Solution 2:

Use an Object as a lookup to get a quick hashtable-backed check. That means using string as your key type, which means normalising the case/ordering/etc of the words first to get a unique key for each combination of words.

// Get key for sentence, removing punctuation and normalising case and word order// eg 'Hello, a  horse!' -> 'x_a hello horse'// the 'x_' prefix is to avoid clashes with any object properties with undesirable// special behaviour (like prototype properties in IE) and get a plain lookup//functiongetSentenceKey(sentence) {
    var trimmed= sentence.replace(/^\s+/, '').replace(/\s+$/, '').toLowerCase();
    var words= trimmed.replace(/[^\w\s]+/g, '').replace(/\s+/, ' ').split(' ');
    words.sort();
    return'x_'+words.join(' ');
}

var lookup= {};
for (var i= sentences.length; i-->0;) {
    var key= getSentenceKey(sentences[i]);
    if (key in lookup)
        sentences.splice(i, 1);
    else
        lookup[key]= true;
}

Would need some work if you need to support non-ASCII characters (\w doesn't play well with Unicode in JS, and the question of what constitutes a word in some languages is a difficult one). Also, is "foo bar foo" the same sentence as "bar bar foo"?

Solution 3:

Here's something to try. I didn't test its performance on large arrays, but I think it should be ok. No jQuery needed.

functionremoveDuplicates(array)
{
    var new_array = [];
    for(var i=0; i<array.length; i++){
        // convert current sentence to sorted, lowercase stringvar sen = array[i].split(" ").sort().join(" ");
        if(new_array.indexOf(sen) == -1){
            // no matches, let's add it!
            new_array.push(sen);
        }
    }
    return new_array;
}

Array.prototype.indexOf = function(item, optional_start_index)
{
    for(var i=optional_start_index||0; i<this.length; i++){
        if(this[i] == item) return i;
    }
    return -1;
}

Use it like this:

var a = ["this is a name", "name is this a", "this name is a", "hello there"];
var clean_array = removeDuplicates(a);
alert(clean_array); // outputs: a is name this,hello there

Solution 4:

JavaScript similar_text Calculates the similarity between two strings

Solution 5:

Sort the array of sentences, and then loop through it and delete an item if it is the same as the previous one:

texts.sort();
for(var i = 1; i < texts.length; i++){
    if(texts[i] === texts[i-1]){
        texts.splice(i,1);
        i--;
     }
}

I tested this in an array with 800 strings, and it seemed reasonably fast.

EDIT: Sorry, didn't read your question very carefully

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