loop through a json object and count elements with the same value in different arrays

Question

I want to loop through a json object and count elements with the same value in different arrays. Here's a sample of my object

var testconn =
{"_total": 3,
    "values":
    [
        {
            "articlesRead": [
                { "articleId": 1001 },
                { "articleId": 1002 },
                { "articleId": 1003 },
                { "articleId": 1004 },
                { "articleId": 1005 },
                { "articleId": 1006 }
            ]
        },
        {
            "articlesRead": [
                { "articleId": 1001 },
                { "articleId": 1002 },
                { "articleId": 2001 },
                { "articleId": 2002 },
                { "articleId": 2003 },
                { "articleId": 2004 }
            ]
        },
        {
            "articlesRead": [
                { "articleId": 1001 },
                { "articleId": 3001 },
                { "articleId": 3002 },
                { "articleId": 3003 },
                { "articleId": 3004 },
                { "articleId": 3005 }
            ]
        }
    ]
}

I want to count how many the ID's exsist in the array. So for this example I shoud have: 1001 x 3 1002 x 2 1003 x 1 1004 x 1 2001 x 1 etc

I'm looping through my object like this

for (i = 0; i < testconn.values.length; i++) {
    var c = testconn.values[i];
    for (j = 0; j < c.articlesRead.length; j++) {
        var a = c.articlesRead[j];
        for (var key in a) {
            if (a[key] is bigger then 1) {
                count a[key]
            }
            return number of

        }
    }
}

shi · Accepted Answer · 2012-08-19 13:39:03Z

3

Just use an object to store the value as a key and increment it:

var id={};
for (var i = 0; i < testconn._total; i++) {
    var c = testconn.values[i];
    for (j = 0; j < c.articlesRead.length; j++) {
        var a = c.articlesRead[j];
        id[a.articleId]= id[a.articleId] ? ++id[a.articleId]: 1;
    }
}
console.log(id);

edited Aug 19, 2012 at 13:39

answered Aug 17, 2012 at 13:45

shi

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2 Comments

pwavg Over a year ago

Excellent, this is what I was looking for (Is it to much to ask to note the if statement in its regular form? I'm not as advanced and would like to understand what you did)

shi Over a year ago

I am using a ternary operator, it makes things shorter, it's the same as:if(id[a.articleId]) { ...} else {...}

Ali · Accepted Answer · 2012-08-17 13:55:35Z

0

Here's an easy way to go about it, using 4 nested for loops, maybe not the most efficient though.

var list = testconn.values;
var dict = {};  


for(var i in list){
    for(var j in list[i]){
        for(var k in list[i][j]){
            for(var l in list[i][j][k]){
                var key = list[i][j][k][l];
                dict[key] = dict[key] ? ++dict[key] : 1;
            }
        }
    }
}

Dict is Now an associative array of what you want.

edited Aug 17, 2012 at 13:55

answered Aug 17, 2012 at 13:48

Ali

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