How to group array of objects to separate arrays by object value?

Question

Example:

array  = [{name:'Anna'}, {name:'Bob'}, {name:'Joe'}, {name:'Anna'}]

I need to group this array by name to get separate arrays like:

array 1 = [{name:'Anna'}, {name:'Anna'}]
array 2 = [{name:'Joe'}]
array 3 = [{name:'Bob'}]

Got no idea how to perfom this. Thanks!

Thats not sorting. That is filtering. Sorting means all contents of 1 bucket. You want to filter the contents of 1 bucket into others. You would need to develop a Set of values, which correlates to the number of buckets. Filter would be run a bunch of times, but you can create a more optimal solution then calling that command N time — Fallenreaper, Mar 04 '19 at 13:46

score 5 · Accepted Answer · answered Mar 04 '19 at 13:46

You mean to group the items by name I think, and not to sort them.

If this is what you want, you can create an intermediate dictionary with Array.reduce(), whose keys are the names and the values are arrays grouping all object with the same name.

Then use Object.values() to enumerate this dictionary and return all groups:

const arr = [{name:'Anna', hello: 1}, {name:'Bob'}, {name:'Joe'}, {name:'Anna'}];

const result = Object.values(arr.reduce((acc, x) => {
  acc[x.name] = [...(acc[x.name] || []), x ];
  return acc;
}, {}));

console.log(result)

Thanks a lot. I started doing myself, but the function was much much bigger than yours. Learned a lot from your example, thanks — Konstantin Kim, Mar 04 '19 at 13:52

score 2 · Answer 2 · answered Mar 04 '19 at 13:47

Group your array by name first and then get the object values. You can use Array.reduce and Object.values for this purpose

var array  = [{name:'Anna'}, {name:'Bob'}, {name:'Joe'}, {name:'Anna'}];

const res = array.reduce((acc, item) => {
   if (acc[item.name]) {
      acc[item.name] = [...acc[item.name], item];
   } else {
      acc[item.name] = [item];
   }
   return acc;
}, {});

console.log(Object.values(res));

score 0 · Answer 3 · answered Mar 04 '19 at 13:50

just convert to object based on value using reduce:

const test = array.reduce((acc, el) => {
  if (!acc[el.name]) {
    return {
       ...acc,
       [el.name]: [el]
    }
  }
  return {
    ...acc,
    [el.name]: [...acc[el.name], el]
  }
}, {});

you got an object with fields, each fields contains requested array of elements

How to group array of objects to separate arrays by object value?

3 Answers3