list-distribution

A helper package for analyzing the distribution of a list based on a field in every item.

How to use it

Construct the distribution with the following parameters

items - this is the list of items you want to operate on. it should be an array, and not be null, undefined or empty.

getter - this is the getter function for the "key" that will be used to compute the distribution

precision - this is the precision you want to have on the key, for instance if you use 100, all buckets will be in 100 intervals

var distribution = new Distribution(items, getter, precision);

var buckets = distribution.getBuckets();

distribution.printBuckets();

An actual example

Let's say you have a list of git repositories, and you want to see what the distribution of forks is over your list.

    var repos = [
        { forks: 10,    watchers: 20    },
        { forks: 14,    watchers: 243   },
        { forks: 14523, watchers: 13442 },
        { forks: 143,   watchers: 4232  },
        { forks: 1555,  watchers: 322   },
        { forks: 1,     watchers: 654   },
        { forks: 103,   watchers: 54    }
    ];

Your getter should be a function that takes in a repo object and selects the interest property off the repo object, in this case the forks count.

var repoForksGetter = function(repo) { 
    return repo.forks; 
};

Now let's construct our distribution object, with a precision of 1000.

var distribution = new Distribution(repos, repoForksGetter, 1000);

And now let's print it to see what's going on

distribution.printBuckets();

This is what you should see

Bucket 0 -> 5
Bucket 1000 -> 1
Bucket 14000 -> 1

This is saying there are 5 repositories with less than 1000 forks, 1 repository with 1000-2000 forks and 1 repository with greater than 15000 forks.

You can also get the raw buckets if there is any extra processing or printing that you would like to do.

var buckets = distribution.getBuckets();

Note that the buckets object is a HashMap.

When printed it should look something like this

HashMap { 
	_data: { 
		'0': [ 0, 5 ], 
		'1000': [ 1000, 1 ], 
		'14000': [ 14000, 1 ] 
	} 
}

You can find the full example in example.js.

Contributing

For any ideas, suggestions for improvement or bugs, feel free to file issues! PRs are more than welcome also! Thanks 🎉

Projects using list-distribution

If you are using list-distribution, feel free to send a pull request to added to this list.

Currently we are used by:

• stories-crawler