[KED-1647] Refactor random data generator, and add layers

src/config.js

@@ -8,15 +8,14 @@ const getDataSource = () => {
   let source;
   const qs = hasWindow && window.location.search.match(/data=(\w+)/);
   const { REACT_APP_DATA_SOURCE } = process.env;
+  const isDemo =
+    hasWindow && window.location.host === 'quantumblacklabs.github.io';
 
   if (qs) {
     source = encodeURIComponent(qs[1]);
   } else if (REACT_APP_DATA_SOURCE) {
     source = REACT_APP_DATA_SOURCE;
-  } else if (
-    hasWindow &&
-    window.location.host === 'quantumblacklabs.github.io'
-  ) {
+  } else if (isDemo) {
     source = 'demo';
   }
   return validateDataSource(source);

src/utils/index.js

@@ -41,6 +41,13 @@ export const randomIndex = n => Math.floor(Math.random() * n);
  */
 export const randomNumber = n => Math.ceil(Math.random() * n);
 
+/**
+ * Get a random number between min and max, inclusive
+ * @param {number} (min) Min number
+ * @param {number} (max) Max number
+ */
+export const randomNumberBetween = (min, max) => randomNumber(max - min) + min;
+
 /**
  * Get a random datum from an array
  * @param {Array} range The array to select a random item from
@@ -61,6 +68,27 @@ export const getRandomName = (n, join = '_') =>
     .map(() => getRandom(LOREM_IPSUM))
     .join(join);
 
+/**
+ * Randomly select a certain number (n) of items from an array (arr).
+ * via https://stackoverflow.com/a/19270021/1651713
+ * @param {array} arr List from which to choose
+ * @param {number} n Number of items to select
+ */
+export const getRandomSelection = (arr, n) => {
+  const result = new Array(n);
+  let len = arr.length;
+  const taken = new Array(len);
+  if (n > len) {
+    return arr;
+  }
+  while (n--) {
+    var x = Math.floor(Math.random() * len);
+    result[n] = arr[x in taken ? taken[x] : x];
+    taken[x] = --len in taken ? taken[len] : len;
+  }
+  return result;
+};
+
 /**
  * Filter duplicate values from an array
  * @param {any} d Datum