spearman

module.exports = {
  spearman: function (values,x,y) {
    var sum         = 0;
    var orderedList = [];
    var length      = values[x].length;
    // for every point in
    for(i=0;i<length;i++){
        orderedList.push([values[x][i], values[y][i]]);
    }

    orderedList.sort(function(a,b){
        return a[0]-b[0]
    });

    for(i=0;i<length;i++){
        orderedList[i].push(i+1);
    }

    orderedList.sort(function(a,b){
        return a[1]-b[1]
    });

    for(i=0;i<length;i++){
        orderedList[i].push(i+1);
    }
    for(i=0;i<length;i++){
        sum+=Math.pow((orderedList[i][2])-(orderedList[i][3]), 2);

    }
    var calc1    = length*length-1
    var calc2    = length*calc1
    var calc3    = 6*(sum/calc2)
    var solution = 1 - calc3;  // reverse answer

    return solution;
    
    //end
  }, 
};