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JavaScript

Posted by Fareez Ahmed
Fareez Ahmed
31 Points

Finding the "Mode" of an Array.

Can folks share functions that are succinct/easy to understand, for finding the mode of an array? Assuming there is only one mode and there will be at least one.

I have stepped through a solution with a tutor but trying to re-read it after having done it is not useful.

1 Answer

Michael Jurgensen
Michael Jurgensen
8,341 Points
Michael Jurgensen
Michael Jurgensen
8,341 Points

Hi Fareez,

First create an empty object to hold the mode. Then create var max (this will be the mode value). Also create a var count to determine which number will be the max. You need to loop through each element in the array. First check the value of mode. If its value is null set it to 1. Otherwise increment the value. Then you want to determine if count is less than the value of mode. 

function mode(input)
 {
    var mode = {};
    var max = 0; 
    var count = 0;

    input.forEach(function(e) 
    {

        if (mode[e] == null) 
        {
            mode[e] = 1; 
        }
        else 
        { 
            mode[e]++; 
        }

        if (count < mode[e])      
       {
            max = e;
            count = mode[e];
        }
    });

    return max;
}

var input = [4,4,4,6,2,7,7,9,9];
alert(mode(input));

EDIT: Easier to understand solution.