Created utility function isIdentical; moved DefsClusters into Clusters file

src/common/utilities.js

@@ -1,4 +1,6 @@
 import moment from 'moment'
+import hash from 'object-hash'
+
 
 let { DATE_FMT, TIME_FMT } = process.env
 if (!DATE_FMT) DATE_FMT = 'MM/DD/YYYY'
@@ -159,6 +161,10 @@ export function selectTypeFromPathWithPoster (path, poster) {
   return { type: typeForPath(path), path, poster }
 }
 
+export function isIdentical (obj1, obj2) {
+  return hash(obj1) === hash(obj2)
+}
+
 export function calcOpacity (num) {
   /* Events have opacity 0.5 by default, and get added to according to how many
    * other events there are in the same render. The idea here is that the
@@ -169,10 +175,16 @@ export function calcOpacity (num) {
 }
 
 export function calcClusterOpacity (pointCount, totalPoints) {
+  /* Clusters represent multiple events within a specific radius. The darker the cluster, 
+  the larger the number of underlying events. We use a multiplication factor (50) here as well
+  to ensure that the larger clusters have an appropriately darker shading. */
   return Math.min(0.85, 0.08 + (pointCount / totalPoints) * 50)
 }
 
 export function calcClusterSize (pointCount, totalPoints) {
+    /* The larger the cluster size, the higher the count of points that the cluster represents.
+    Just like with opacity, we use a multiplication factor to ensure that clusters with higher point
+    counts appear larger. */
   return Math.min(50, 10 + (pointCount / totalPoints) * 150)
 }