identifying identical elements within an array

Question

identifying identical elements within an array

Once I received various user images, the resulting array looks like this:

[
    { label: "portrait", owner: "Jon" },
    { label: "house", owner: "Jim" },
    { label: "portrait", owner: "Jim" },
    { label: "portrait", owner: "Jane" },
    { label: "cat", owner: "Jane" }
]

In order to highlight entries with duplicate label values in the array (in this case: "portrait"), I am seeking assistance.

Ideally, I would like to flag items with a repeat occurrence of the label, distinguishing between those flagged as A for being repeated later in the array and those flagged as B for being the final occurrence (for example, both Jon's and Jim's portraits are flagged as A, while Jane's is flagged as B).

Any support provided on this matter would be greatly valued!

javascript algorithm duplicates

Answer 1

Answer №1

Not quite sure about your intentions, but perhaps aggregating the data could be the solution?

var data = [
    { name: "portrait", owner: "Jon" },
    { name: "house", owner: "Jim" },
    { name: "portrait", owner: "Jim" },
    { name: "portrait", owner: "Jane" },
    { name: "cat", owner: "Jane" }
];

var byName = {};

for (var i = 0, l = data.length; i < l; ++i) {
    if (!byName[data[i].name]){
        byName[data[i].name] = [];
    }
    byName[data[i].name].push(data[i].owner);
}

// byName == {portrait: ["Jon", "Jim", "Jane"], house: ["Jim"], cat: ["Jane"]}

var byOwner = {};

for (var i = 0, l = data.length; i < l; ++i) {
    if (!byOwner[data[i].owner]) {
        byOwner[data[i].owner] = [];
    }
    byOwner[data[i].owner].push(data[i].name);
}

Alternatively, you might prefer this approach:

var data = [
    { name: "portrait", owner: "Jon" },
    { name: "house", owner: "Jim" },
    { name: "portrait", owner: "Jim" },
    { name: "portrait", owner: "Jane" },
    { name: "cat", owner: "Jane" }
];

var byName = [];

for (var i = 0, l = data.length; i < l; ++i) {
    var done = false;
    for (var j = 0, k = data.length; j < k; ++j) {
        if (byName[j] && byName[j].name == data[i].name) {
            byName[j].data.push(data[i].owner);
            done = true;
        }
    }
    if (!done) {
        byName.push({name: data[i].name, data: [data[i].owner]});
    }
}

/*
byName == [
    {name: "portrait", data: ["Jon", "Jim", "Jane"]},
    {name: "house", data: ["Jim"]},
    {name: "cat", data: ["Jane"]}
] */

Let's throw in some random code for a bit of fun!

Answer 2

Not quite sure about your intentions, but perhaps aggregating the data could be the solution?

var data = [
    { name: "portrait", owner: "Jon" },
    { name: "house", owner: "Jim" },
    { name: "portrait", owner: "Jim" },
    { name: "portrait", owner: "Jane" },
    { name: "cat", owner: "Jane" }
];

var byName = {};

for (var i = 0, l = data.length; i < l; ++i) {
    if (!byName[data[i].name]){
        byName[data[i].name] = [];
    }
    byName[data[i].name].push(data[i].owner);
}

// byName == {portrait: ["Jon", "Jim", "Jane"], house: ["Jim"], cat: ["Jane"]}

var byOwner = {};

for (var i = 0, l = data.length; i < l; ++i) {
    if (!byOwner[data[i].owner]) {
        byOwner[data[i].owner] = [];
    }
    byOwner[data[i].owner].push(data[i].name);
}

Alternatively, you might prefer this approach:

var data = [
    { name: "portrait", owner: "Jon" },
    { name: "house", owner: "Jim" },
    { name: "portrait", owner: "Jim" },
    { name: "portrait", owner: "Jane" },
    { name: "cat", owner: "Jane" }
];

var byName = [];

for (var i = 0, l = data.length; i < l; ++i) {
    var done = false;
    for (var j = 0, k = data.length; j < k; ++j) {
        if (byName[j] && byName[j].name == data[i].name) {
            byName[j].data.push(data[i].owner);
            done = true;
        }
    }
    if (!done) {
        byName.push({name: data[i].name, data: [data[i].owner]});
    }
}

/*
byName == [
    {name: "portrait", data: ["Jon", "Jim", "Jane"]},
    {name: "house", data: ["Jim"]},
    {name: "cat", data: ["Jane"]}
] */

Let's throw in some random code for a bit of fun!

Answer 3

Answer №2

To optimize the picture array, my recommendation would be to iterate through each object in the array and assign a flag based on whether it is a duplicate or not. The concept is illustrated below with a working example. Each duplicated item will receive an 'A' flag, while the last duplicate will be marked with a 'B'. Objects that are unique will remain unflagged.

var picture_array = [
        {label: 'portrait', owner: "Jon"},
        {label: 'house', owner: "Jim"},
        {label: 'portrait', owner: "Jim"},
        {label: 'portrait', owner: "Jane"},
        {label: 'cat', owner: "Jane"}
    ],
    length = picture_array.length;

//Iterate through the picture_array

for(var i = 0; i < length; i++) {
    var picture = picture_array[i],
        label = picture.label;

    //Skip if the picture has already been flagged
    if (picture.flagged) {
       continue;
    }

    //Check for duplicates by comparing labels within the array
    var picture_a = picture;
    for(var j = i + 1; j < length; j++) {
        var picture_b = picture_array[j];

        //Flag matching duplicates accordingly
        if (picture_a.label == picture_b.label) {
            picture_a.flagged = 'A';
            picture_b.flagged = 'B';
            picture_a = picture_b;
        }
    }
}

Answer 4

To optimize the picture array, my recommendation would be to iterate through each object in the array and assign a flag based on whether it is a duplicate or not. The concept is illustrated below with a working example. Each duplicated item will receive an 'A' flag, while the last duplicate will be marked with a 'B'. Objects that are unique will remain unflagged.

var picture_array = [
        {label: 'portrait', owner: "Jon"},
        {label: 'house', owner: "Jim"},
        {label: 'portrait', owner: "Jim"},
        {label: 'portrait', owner: "Jane"},
        {label: 'cat', owner: "Jane"}
    ],
    length = picture_array.length;

//Iterate through the picture_array

for(var i = 0; i < length; i++) {
    var picture = picture_array[i],
        label = picture.label;

    //Skip if the picture has already been flagged
    if (picture.flagged) {
       continue;
    }

    //Check for duplicates by comparing labels within the array
    var picture_a = picture;
    for(var j = i + 1; j < length; j++) {
        var picture_b = picture_array[j];

        //Flag matching duplicates accordingly
        if (picture_a.label == picture_b.label) {
            picture_a.flagged = 'A';
            picture_b.flagged = 'B';
            picture_a = picture_b;
        }
    }
}

identifying identical elements within an array

Answer №1

Answer №2

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