Added a bunch of commentary

node_ppa.js

@@ -4,6 +4,8 @@ var qs = require('querystring');
 var sylvester = require('sylvester');
 var async = require('async');
 
+// Nearest neighbor distance calculator function
+// Takes the coordinates array from the query and build a D matrix
 function nndist(query, res, callback) {
     var coords = JSON.parse(query.coordinates);
     var darray = [];
@@ -48,9 +50,16 @@ function nndist(query, res, callback) {
             // }
     // });
 
+    // The row builder function creates a new row of values in the D matrix
+    // It is called recursively until the coordinates array is traversed
+    // Once all the coordinates have been iterated over a new array is used
+    // to 
     function rowBuilder(i) {
         if(i<coords.length) {
             darray.push([]);
+
+            // The distance calculation function calculates the distance between the current point/row (i)
+            // and every other point (j) then pushed that value into the current row and traverses the row recursively
             function distCalc(j) {
                 if(j<coords.length) {
                     // Distance formula
@@ -67,6 +76,8 @@ function nndist(query, res, callback) {
             distCalc(0);
         } else {
             var nnarray = [];
+
+            // The row sorter function iterates of the D matrix rows and sorts them in ascending order
             function rowSorter(i) {
                 if(i<darray.length) {
                     // Array.min = function( array ){
@@ -78,6 +89,8 @@ function nndist(query, res, callback) {
                     rowSorter(i+1);
                 } else {
                     var nndistsum = 0;
+
+                    // Iterates over the sorted rows and adds the value of shortest distance to the running total
                     function meanDist(j) {
                         if(j<nnarray.length) {
                             nndistsum += nnarray[j];
@@ -94,12 +107,14 @@ function nndist(query, res, callback) {
     }
     rowBuilder(0);
 
+    // Respond with the stringified nearest neighbor value
     var responseobjstring = JSON.stringify(nnvalue);
     res.setHeader('Content-Type', 'application/json');
     res.end(callback + '(' + responseobjstring + ')');
-
 }
 
+// Create a server and parse the url, query string, and callback
+// Switch to direct incoming request to functions
 var server = http.createServer(function(req, res) {
 
     var url = parse(req.url);