✨ sampleSize

Author: tangweikun

src/collection/__tests__/sampleSize.spec.js

@@ -0,0 +1,9 @@
+import { sampleSize } from '..'
+
+test('sampleSize', () => {
+ console.log(sampleSize([1, 2, 3], 2))
+ console.log(sampleSize([1, 2, 3], 3))
+ console.log(sampleSize([1, 2, 3], 4))
+ console.log(sampleSize([1, 2, 3, 4, 5], 3))
+ console.log(sampleSize([1, 2, 3, 4, 5], 4))
+})

src/collection/groupBy.js

@@ -6,7 +6,7 @@
 export const groupBy = (arr, fn = x => x) =>
  arr.reduce((res, el) => {
  const foo = typeof fn === 'function' ? fn(el) : el[fn]
- if (res[foo]) res[foo].push(el)
- else res[foo] = [el]
+ res[foo] = res[foo] || []
+ res[foo].push(el)
  return res
  }, {})

src/collection/index.js

@@ -1,2 +1,3 @@
 export * from './countBy'
 export * from './groupBy'
+export * from './sampleSize'

src/collection/sampleSize.js

@@ -0,0 +1,14 @@
+// Gets n random elements at unique keys from collection up to the size of collection.
+
+// TODO:
+
+export const sampleSize = (nums, n = 1) => {
+ const foo = [...nums]
+ const len = n > nums.length ? nums.length : n
+
+ let res = []
+ for (let i = 0; i < len; i++) {
+ res.push(...foo.splice(Math.round(Math.random() * (len - 1 - i)), 1))
+ }
+ return res
+}