Getting Unique value from an array

Question

So I have 2 arrays like these ...

var browser_names = ["Firefox", "Maxthon", "Opera", "Opera", "Chrome", "Chrome", "Edge", "Firefox"]

var user_count = [3, 3, 3, 3, 7, 20, 94, 142]

I want results like these

var result_browser_names = ["Firefox", "Maxthon", "Opera", "Chrome", "Edge"]

var result_user_count = [145, 3, 6, 27, 94]

As you can see 'result_browser_names' contains unique browser name values & 'result_user_count' contains 'sum of users' for each type of browser.

I have seen this solution, which works great for a single array. In my case I have 2 arrays ....

Any help is very much appreciated. Thanks

by seeing your example, I assume the 2 arrays should be consistent and align with each other all the time? If that's the case, why isn't the solution you link to not working, by doing them separately on both arrays? — shole
– shole, Commented Sep 5, 2016 at 2:41
Do you have any specific problem with adapting the one-array solution to two arrays? — sth
– sth, Commented Sep 5, 2016 at 2:42
Hi shole & sth. If I run the single array solution to my 'user_count' array. I will get incorrect results. — Slyper
– Slyper, Commented Sep 5, 2016 at 2:53
Please post the code of what you tried. What happened? What did you expect to happen? What in particular is unclear? — Robert
– Robert, Commented Sep 5, 2016 at 3:46
Hi Robert, Seems like you haven't seen the answer below by Philip. Thanks — Slyper
– Slyper, Commented Sep 5, 2016 at 5:39

philip yoo · Accepted Answer · 2016-09-05 02:59:13Z

I'd suggest using an object. Assuming your 2 arrays will always match in length:

var browser_names = ["Firefox", "Maxthon", "Opera", "Opera", "Chrome", "Chrome", "Edge", "Firefox"]
var user_count = [3, 3, 3, 3, 7, 20, 94, 142]
var lib = {}

for (var i=0; i < browser_names.length; i++) {
  if (lib[browser_names[i]] != undefined) {
    lib[browser_names[i]] += user_count[i];
  } else {
    lib[browser_names[i]] = user_count[i];
  }
}

This should give you the browser names and the cumulative user counts for each browser saved within object lib

Also, for the if conditional in the loop, you could also do:

for (var i=0; i < browser_names.length; i++) {
  if (lib.hasOwnProperty(browser_names[i])) {
    lib[browser_names[i]] += user_count[i];
  } else {
    lib[browser_names[i]] = user_count[i];
  }
}

Also, I know your original question was an output to an array. You can easily loop through the keys of the object to get each of their respective browser names and user counts as well:

for (var k in lib) {
  console.log(k);         // Browser Names
  console.log(lib[k]);    // Their respective user counts
}

Nina Scholz · Accepted Answer · 2016-09-05 06:39:11Z

0

You could use a single loop and the help from an object as reference to the result arrays.

var browser_names = ["Firefox", "Maxthon", "Opera", "Opera", "Chrome", "Chrome", "Edge", "Firefox"],
    user_count = [3, 3, 3, 3, 7, 20, 94, 142],
    result_browser_names = [],
    result_user_count = [];

browser_names.forEach(function (b, i) {
    if (!(b in this)) {
        this[b] = result_browser_names.push(b) - 1;
        result_user_count.push(0);
    }
    result_user_count[this[b]] += user_count[i];
}, Object.create(null));

console.log(result_browser_names);
console.log(result_user_count);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Sep 5, 2016 at 6:39

Nina Scholz

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