Merge pull request #64 from Cambalab/63-As-a-user-i-want-to-get-a-sub…

…group-of-arrays-from-given-options

63 as a user i want to get a subgroup of arrays from given options

README.md

@@ -295,13 +295,42 @@ This is how the script knows we want to nest objects
 
 ```json
 {
-  "whichDisneyMovieToWatchTonight": {
+  "whichMovieToWatchTonight": {
     "type": "randomElementInArray",
-    "value": ["Frozen", "Mulan", "The Lion King", "Aladdin"]
+    "value": ["Frozen", "Mulan", "The Lion King", "Aladdin", "Pulp Fiction"]
   }
 }
 ```
 
+*output*
+```json
+{
+  "whichMovieToWatchTonight": "Pulp Fiction"
+}
+```
+
+##### randomElementsInArray
+
+*This one returns a random group of elements from an array of options.*
+
+`value: Array` a list of options to pick from.
+
+```json
+{
+  "whichMoviesToWatchTonight": {
+    "type": "randomElementsInArray",
+    "value": ["Frozen", "Mulan", "The Lion King", "Aladdin", "Pulp Fiction"]
+  }
+}
+```
+
+*output*
+```json
+{
+  "whichMoviesToWatchTonight": ["Pulp Fiction", "Aladdin"]
+}
+```
+
 ##### randomNumberBetweenWithString
 
 *Just another version of randomNumberBetween that accepts a range of numbers, a prefix as a string and a suffix as a string*

lib/helpers/index.js

@@ -2,13 +2,15 @@ import './misc'
 import {
   incrementNumber,
   randomBetween,
-  randomArray,
-  randomBetweenWithString
+  randomBetweenWithString,
+  randomElementInArray,
+  randomElementsInArray,
 } from './numbers'
 
 export const numbers = {
   incrementNumber,
   randomBetween,
-  randomArray, 
-  randomBetweenWithString
+  randomBetweenWithString,
+  randomElementInArray,
+  randomElementsInArray,
 }

lib/helpers/numbers.js

@@ -3,9 +3,18 @@ const randomBetween = ([min, max]) => {
   return Math.floor(Math.random()*(max-min+1)+min)
 }
 
-var randomArray = function randomElementInArray(arr) {
-  const ele = Math.floor(Math.random()*(arr.length - 1))
-  return arr[ele];
+const randomElementInArray = function randomElementInArray(value) {
+  const ele = Math.floor(Math.random() * (value.length - 1))
+  return value[ele];
+}
+
+const randomElementsInArray = (value) => {
+  const subArray = [...value]
+  for (let i = subArray.length - 1; i > 0; i--) {
+      const j = Math.floor(Math.random() * (i + 1));
+      [subArray[i], subArray[j]] = [subArray[j], subArray[i]];
+  }
+  return subArray.slice(0, Math.floor(Math.random() * subArray.length) || 1);
 }
 
 const randomBetweenWithString = (value, {
@@ -26,6 +35,7 @@ const incrementNumber = (value, { index, from = 0 }) => {
 export {
   incrementNumber,
   randomBetween,
-  randomArray,
   randomBetweenWithString,
+  randomElementInArray,
+  randomElementsInArray,
 }

lib/parse-model.js

@@ -121,7 +121,8 @@ const modelAttributeTypes = {
   // ---- numbers
   incrementNumber: numbers.incrementNumber,
   randomNumberBetween: numbers.randomBetween,
-  randomElementInArray: numbers.randomArray,
+  randomElementInArray: numbers.randomElementInArray,
+  randomElementsInArray: numbers.randomElementsInArray,
   randomNumberBetweenWithString: numbers.randomBetweenWithString
 }
 

test/unit/helpers/numbers.spec.js

@@ -17,14 +17,22 @@ describe('Numbers', () => {
     expect(randomNumber).to.be.within(from, to)
   })
 
-  it('randomArray - returns a a random value from an array', () => {
-    const { randomArray } = numbers
+  it('randomElementInArray - returns a random value from an array', () => {
+    const { randomElementInArray } = numbers
     const arr = ['One','Two','Three','Four]']
-    const element = randomArray(arr)
+    const element = randomElementInArray(arr)
 
     expect(arr).to.include(element);
   })
 
+  it('randomElementsInArray - returns a random subgroup from an array', () => {
+    const { randomElementsInArray } = numbers
+    const arr = ['One','Two','Three','Four]']
+    const elements = randomElementsInArray(arr)
+
+    expect(elements).to.be.an('array').that.is.not.empty;
+    // expect(arr).to.include(element);
+  })
 
   it('randomBetweenWithString - returns a number between 1 and 2500000 with prefix \'#\' and suffix \'*\'', () => {
     const { randomBetweenWithString } = numbers