Find similarities between an array of string elements and an array of object properties

Question

Find similarities between an array of string elements and an array of object properties

Let's dive into this: for the items listed in foo, how can we identify all the positive matches with the string attributes in each object within array bar? Here's a quick example:

var foo = ['one', 'two', 'three'];
var bar = [
        {   
            integer: 1,
            string: 'one'
        },
        {   
            integer: 3,
            string: 'three'
        }       
    ];

javascript arrays object

Answer 1

Answer №1

To start, create a set including all elements within foo to prevent quadratic complexity:

var fooSet = {};    
for(var i = 0; i < foo.length; i++) {
    var e = foo[i];
    fooSet[e] = true;
}

Next, iterate through bar and collect any matches found:

var matches = [];
for(var i = 0; i < bar.length; i++) {
    var e = bar[i];
    if(fooSet[e.string]) {
           matches.push(e);
    }
}

Once completed, the matches array will store the elements in bar that correspond with those in foo.

For a demonstration, refer to the following live example:

http://jsfiddle.net/mfAc4/

Answer 2

To start, create a set including all elements within foo to prevent quadratic complexity:

var fooSet = {};    
for(var i = 0; i < foo.length; i++) {
    var e = foo[i];
    fooSet[e] = true;
}

Next, iterate through bar and collect any matches found:

var matches = [];
for(var i = 0; i < bar.length; i++) {
    var e = bar[i];
    if(fooSet[e.string]) {
           matches.push(e);
    }
}

Once completed, the matches array will store the elements in bar that correspond with those in foo.

For a demonstration, refer to the following live example:

http://jsfiddle.net/mfAc4/

Answer 3

Answer №2

Iterate through one of the arrays and compare each item with the other:

var matches = [],
    i, j;

for (i=0; i < bar.length; i++)
    if (-1 != (j = foo.indexOf(bar[i].string)))
       matches.push(foo[j]);

// matches is ['one', 'three']

If you want matches to hold the elements from bar instead of foo, simply update the .push() statement to matches.push(bar[i]);.

This method assumes that older browsers lacking support for .indexOf() on arrays are not a concern, or that a shim can be utilized.

Answer 4

Iterate through one of the arrays and compare each item with the other:

var matches = [],
    i, j;

for (i=0; i < bar.length; i++)
    if (-1 != (j = foo.indexOf(bar[i].string)))
       matches.push(foo[j]);

// matches is ['one', 'three']

If you want matches to hold the elements from bar instead of foo, simply update the .push() statement to matches.push(bar[i]);.

This method assumes that older browsers lacking support for .indexOf() on arrays are not a concern, or that a shim can be utilized.

Answer 5

Answer №3

These two methods are effective, depending on how you intend to manipulate the data.

http://jsfiddle.net/KxgQW/5/

APPROACH ONE

// Deciding to implement both options
var wayOneArrayFOO = Array();
var wayOneArrayBAR = Array();

var fooLength = foo.length;
var barLength = bar.length;

/*THE TRICK*/
// Looping through foo
for(i=0;i<fooLength;i++){

    // Nested loop to iterate over bar while looping through foo        
    for(j=0;j<barLength;j++){
        if(foo[i] == bar[j].string){
            wayOneArrayFOO.push(i);
            wayOneArrayBAR.push(j);    
        }
    }

}

APPROACH TWO

// Storing values of foo and bar respectively
var wayTwoArrayFOO = Array();
var wayTwoArrayBAR = Array();      

/*THE TRICK*/      
// Looping through foo
for(i=0;i<fooLength;i++){

    // Nested loop for iterating over bar while looping through foo       
    for(j=0;j<barLength;j++){
        if(foo[i] == bar[j].string){
            wayTwoArrayFOO.push(foo[i]);
            wayTwoArrayBAR.push(bar[j]);    
        }
    }

}

Answer 6

These two methods are effective, depending on how you intend to manipulate the data.

http://jsfiddle.net/KxgQW/5/

APPROACH ONE

// Deciding to implement both options
var wayOneArrayFOO = Array();
var wayOneArrayBAR = Array();

var fooLength = foo.length;
var barLength = bar.length;

/*THE TRICK*/
// Looping through foo
for(i=0;i<fooLength;i++){

    // Nested loop to iterate over bar while looping through foo        
    for(j=0;j<barLength;j++){
        if(foo[i] == bar[j].string){
            wayOneArrayFOO.push(i);
            wayOneArrayBAR.push(j);    
        }
    }

}

APPROACH TWO

// Storing values of foo and bar respectively
var wayTwoArrayFOO = Array();
var wayTwoArrayBAR = Array();      

/*THE TRICK*/      
// Looping through foo
for(i=0;i<fooLength;i++){

    // Nested loop for iterating over bar while looping through foo       
    for(j=0;j<barLength;j++){
        if(foo[i] == bar[j].string){
            wayTwoArrayFOO.push(foo[i]);
            wayTwoArrayBAR.push(bar[j]);    
        }
    }

}

Answer 7

Answer №4

Here is a code snippet that matches keys from one array to another:

// Define foo & bar arrays here

// Store all the keys from the foo array in a dictionary (object)
var matchSet = {};
for (var item in foo)
{
    var val = foo[item];
    matchSet[val] = 1;
}

// Check if items in the bar array have a matching key in the matchSet
// If so, add it to the matches array
var matches = [];
for (var i=0; i < bar.length; i++)
{
    var item = bar[i];
    if (matchSet.hasOwnProperty(item['string']))
    {
        matches.push(item['string']);
    }
}

// Output the matched strings using node
for (var i in matches)
{
    console.log(matches[i]);
}

Outputs:

match: one
match: three

Please note that this code is intended to be run interactively using node.

Answer 8

Here is a code snippet that matches keys from one array to another:

// Define foo & bar arrays here

// Store all the keys from the foo array in a dictionary (object)
var matchSet = {};
for (var item in foo)
{
    var val = foo[item];
    matchSet[val] = 1;
}

// Check if items in the bar array have a matching key in the matchSet
// If so, add it to the matches array
var matches = [];
for (var i=0; i < bar.length; i++)
{
    var item = bar[i];
    if (matchSet.hasOwnProperty(item['string']))
    {
        matches.push(item['string']);
    }
}

// Output the matched strings using node
for (var i in matches)
{
    console.log(matches[i]);
}

Outputs:

match: one
match: three

Please note that this code is intended to be run interactively using node.

Find similarities between an array of string elements and an array of object properties

Answer №1

Answer №2

Answer №3

Answer №4

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