arrays - Javascript number data grouping and outlier removal -

i have array follows:

var myarray = [3, 6, 8, 9, 16, 17, 19, 37]

i needing remove outliers group remaining data distinctive groups appear. in case 37 removed outlier , [3, 6, 8, 9] returned first group , [16, 17, 19] returned second.

here second example

var mysecondarray = [80, 90, 100, 200, 280, 281, 287, 500, 510, 520, 800]

200 , 800 removed outlier, [80, 90, 100] first group, [280, 281, 287] second , [500, 510, 520] third.

i have written code works remove outliers on outside simple enough using first , third quartile. in other words have no problem removing 800 mysecondarray outlier. not remove 280 outlier.

i suppose outlier defined group less n members real issue what efficient method divide data appropriate number of groups?

any appreciated!

jsfiddle demo

this simple implementation, may not perfect solution set of problems should suffice example - may work beyond well.

by looking @ average distance between numbers, , comparing distance distance on either side of each number, should possible remove outliers. following, same metric can used grouping.

function sum(arr){  	return arr.filter(i => !isnan(i)).reduce((p,c) => p+c,0);  };  function avg(arr){  	return sum(arr) / arr.length;  }  function groupby(arr,dist){    var groups = [];    var group = [];    for(var = 0; < arr.length; i++){      group.push(arr[i]);      if(arr[i+1] == undefined)continue;      if(arr[i+1] - arr[i] > dist){        groups.push(group);        group = [];      }    }    groups.push(group);    return groups;  }  function groupoutlier(arr){    var distbefore = arr.map((c,i,a) => == 0 ? undefined : c - a[i-1]);    var distafter = arr.map((c,i,a) => == a.length-1 ? undefined : a[i+1] - c);      var avgdist = avg(distafter);      var result = arr.filter((c,i,a) => !(distbefore[i] == undefined ? distafter[i] > avgdist : (distafter[i] == undefined ? distbefore[i] > avgdist : distbefore[i] > avgdist && distafter[i] > avgdist)));        return groupby(result,avgdist);  }    var myarray = [3, 6, 8, 9, 16, 17, 19, 37];    console.log(groupoutlier(myarray));    var mysecondarray = [80, 90, 100, 200, 280, 281, 287, 500, 510, 520, 800]    console.log(groupoutlier(mysecondarray));