Javascript - Convert one Array into two after Group-by in

Question

I have array like below

myArray = ["foo", "bar", "foo", "bar", "bar", "bar", "zoom"]

I want output like this

nameArray = ["foo", "bar", "zoom"]

and

qtyArray = [2, 4, 1]

I will be using Plotly out of resulting two arrays to draw bar plot.

TIA

This answer may be helpful https://stackoverflow.com/a/35101824/7692859 — Anis R., Oct 18 '19 at 13:52

score 2 · Accepted Answer · answered Oct 18 '19 at 13:53

You could take a Map and get the keys and values.

var array = ["foo", "bar", "foo", "bar", "bar", "bar", "zoom"],
    map = array.reduce((m, v) => m.set(v, (m.get(v) || 0) + 1), new Map),
    values = [...map.keys()],
    counts = [...map.values()];

console.log(...values);
console.log(...counts);

score 1 · Answer 2 · answered Oct 18 '19 at 13:51

You can use reduce function. Inside the callback check if the accumulator object have a key by name of foo or bar or zoom. If it is there then increase the count by 1 else create a key by that name and put 1 as value. Then you can use Object.keys to create an array of keys which will be foo,bar & zoom & Object.values to get an array of the counts

let myArray = ["foo", "bar", "foo", "bar", "bar", "bar", "zoom"];

let newData = myArray.reduce(function(acc, curr) {
  if (acc[curr]) {
    acc[curr] += 1;
  } else {
    acc[curr] = 1;

  }
  return acc;
}, {});

let nameArray = Object.keys(newData);
let qtyArray = Object.values(newData);
console.log(nameArray, qtyArray)

FYI: If the array has *integer-like* items, the order of `Object.keys()` will change. — adiga, Oct 18 '19 at 13:55

jidexl21 · Answer 3 · 2019-10-18T14:09:02.153

0

var myArray = ["foo", "bar", "foo", "bar", "bar", "bar", "zoom"]; 
var arr = {}
myArray.map(function(x){
  if(typeof(arr[x])=="undefined") {arr[x] =0;}
  arr[x]++;
})

var arr1 = Object.keys(arr);
arr2 = arr1.map(x=>arr[x])


/* arr1
foo,bar,zoom
*/

/* arr2
2,4,1
*/

edited Oct 18 '19 at 14:09

answered Oct 18 '19 at 14:02

jidexl21

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Javascript - Convert one Array into two after Group-by in

3 Answers3