Formatted with standard

Author: MarkSFrancis

Dynamic-Programming/Shuf.js

@@ -3,10 +3,10 @@ Given a data set of an unknown size,
 Get a random sample in a random order
 It's used in data analytics, often as a way to get a small random sample from a data lake or warehouse, or from a large CSV file
 */
-function shuf(datasetSource, sampleSize) {
- let output = fillBaseSample(datasetSource, sampleSize);
+function shuf (datasetSource, sampleSize) {
+ const output = fillBaseSample(datasetSource, sampleSize)
 
- return randomizeOutputFromDataset(datasetSource, output);
+ return randomizeOutputFromDataset(datasetSource, output)
 }
 
 /**
@@ -16,39 +16,39 @@ function shuf(datasetSource, sampleSize) {
  * @returns {Array.<T>} The random sample, as an array
  * @template T
  */
-function fillBaseSample(datasetSource, sampleSize) {
- let filledIndexes = [];
- let output = new Array(sampleSize);
+function fillBaseSample (datasetSource, sampleSize) {
+ let filledIndexes = []
+ let output = new Array(sampleSize)
 
  // Spread data out filling the array
  while (true) {
- const iterator = datasetSource.next();
- if (iterator.done) break;
+ const iterator = datasetSource.next()
+ if (iterator.done) break
 
- let insertTo = Math.floor(Math.random() * output.length);
+ let insertTo = Math.floor(Math.random() * output.length)
  while (filledIndexes.includes(insertTo)) {
- insertTo++;
+ insertTo++
  if (insertTo === output.length) {
- insertTo = 0;
+ insertTo = 0
  }
  }
  output[insertTo] = {
- value: iterator.value,
- };
+ value: iterator.value
+ }
 
- filledIndexes = [...filledIndexes, insertTo];
+ filledIndexes = [...filledIndexes, insertTo]
 
  if (filledIndexes.length === sampleSize) {
- break;
+ break
  }
  }
 
  if (filledIndexes.length < output.length) {
  // Not a large enough dataset to fill the sample - trim empty values
- output = output.filter((_, i) => filledIndexes.includes(i));
+ output = output.filter((_, i) => filledIndexes.includes(i))
  }
 
- return output.map((o) => o.value);
+ return output.map((o) => o.value)
 }
 
 /**
@@ -58,22 +58,22 @@ function fillBaseSample(datasetSource, sampleSize) {
  * @returns {Array.<T>} The random sample, as an array
  * @template T
  */
-function randomizeOutputFromDataset(datasetSource, output) {
- const newOutput = [...output];
- let readSoFar = output.length;
+function randomizeOutputFromDataset (datasetSource, output) {
+ const newOutput = [...output]
+ let readSoFar = output.length
 
  while (true) {
- const iterator = datasetSource.next();
- if (iterator.done) break;
- readSoFar++;
+ const iterator = datasetSource.next()
+ if (iterator.done) break
+ readSoFar++
 
- const insertTo = Math.floor(Math.random() * readSoFar);
+ const insertTo = Math.floor(Math.random() * readSoFar)
  if (insertTo < newOutput.length) {
- newOutput[insertTo] = iterator.value;
+ newOutput[insertTo] = iterator.value
  }
  }
 
- return newOutput;
+ return newOutput
 }
 
 const main = () => {
@@ -82,15 +82,15 @@ const main = () => {
  * @param {number} length The number of data items to generate
  * @returns {Iterable<number>} Random iterable data
  */
- function* generateRandomData(length) {
- const maxValue = Math.pow(2, 31) - 1;
+ function * generateRandomData (length) {
+ const maxValue = Math.pow(2, 31) - 1
  for (let i = 0; i < length; i++) {
- yield Math.floor(Math.random() * maxValue);
+ yield Math.floor(Math.random() * maxValue)
  }
  }
 
- const source = generateRandomData(1000);
- const result = shuf(source, 10);
+ const source = generateRandomData(1000)
+ const result = shuf(source, 10)
  console.log(result)
 }
 main()