Dynamic Array Value Count

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How would I go about doing this, except with dynamic values?

var counts = []
var dates= [ "28/05/2013", "27/05/2013", "28/05/2013", "26/05/2013", "28/05/2013" ];

How would I get a count of the duplicated array values? So how many 28/05/2013 etc. The dates are all dynamic, so I can't just search for set values. I just can't get my head around how I would do this.

I may just scrap this idea, and get the value count from the last 10 days or something... but this may come in handy later(if it is even possible to do this).

The solutions on the link you provided should work for you.. loop throught your array and invoke the function provided there. — Yotam Omer
– Yotam Omer, Commented May 28, 2013 at 9:27

Bergi · Accepted Answer · 2013-05-28 09:37:05Z

3

This will do it:

var counts = {};
for (var i=0; i<dates.length; i++)
    if (dates[i] in counts)
        counts[dates[i]]++;
    else
        counts[dates[i]] = 1;

The result will be

> counts
{
    "28/05/2013": 3,
    "27/05/2013": 1,
    "26/05/2013": 1
}

answered May 28, 2013 at 9:37

Bergi

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Imran · Accepted Answer · 2013-05-28 09:35:42Z

3

Make counts an object to perform duplicate detection in constant time.

var counts = {}

for (var i = 0; i < dates.length; i++) {
    var date = dates[i];
    if (counts[date] === undefined) {
        counts[date] = 0;
    }
    counts[date] += 1;
}

console.log(counts);

answered May 28, 2013 at 9:35

Imran

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1 Comment

Gary Kenyon Over a year ago

This works PERFECTLY. I think I understand how you're doing this.

Dineshkani · Accepted Answer · 2013-05-28 09:33:11Z

0

Try like this

Updated

var dates= [ "28/05/2013", "27/05/2013", "28/05/2013", "26/05/2013", "28/05/2013" ];
var findStr = "28/05/2013";
var indexs = dates.indexOf(findStr,0),count=0;
for (var i=0;i< dates.length;i++){
if (indexs >= 0){
    indexs = dates.indexOf(findStr,indexs + 1);
    count++;
}
}
alert(count);

See Demo

answered May 28, 2013 at 9:33

Dineshkani

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3 Comments

Sysyphus Over a year ago

Try swapping the first date to 27 from 28, and you'll see that your code is rather broken.

Gary Kenyon Over a year ago

I'm looking for a count of each duplicated element too, I'm afraid.

Sysyphus Over a year ago

Better, but you still have a hardcoded value to find, so all you're doing is counting the number of occurrences of one value. Just sticking a loop around your code going foreach findstr in dates would work...but is also n*2 which is much slower than the solution needs to be. There is an easy optimisation you can add in then though.

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