Compare array with object key and group in javascript

Question

I need to compare the key of an object in an array, I need to group based on the key value

const days = [
    {'name':'Mon','value':1}, 
    {'name':'Tue','value':5},
    {'name':'Wed','value':10},
    {'name':'Wed','value':30},
    {'name':'Fri','value':18},
    {'name':'Sat','value':80},
    {'name':'Sat','value':90},
    {'name':'Sun','value':20},
]

I need to group like this

const result [[1],[5], [10, 30], [18], [80, 90], [20]]

I am very new to javascript, I am not going to do this. if its possible in lodash - es6, everything will be fine.

Answer 1

You can take an object the same day and filter the result to get only filled arrays.

var days = [{ name: 'Mon', value: 1 }, { name: 'Tue', value: 5 }, { name: 'Wed', value: 10 }, { name: 'Wed', value: 30 }, { name: 'Fri', value: 18 }, { name: 'Sat', value: 80 }, { name: 'Sat', value: 90 }, { name: 'Sun', value: 20 }], 
    slot = { Mon: 0, Tue: 1, Wed: 2, Thu: 3, Fri: 4, Sat: 5, Sun: 6 },
    result = [];

days.forEach(({ name, value }) => (result[slot[name]] = result[slot[name]] || []).push(value));

result = result.filter(Boolean);

console.log(result);

Run code

Answer 2

You can simply iterate over an object and create a key map for the data, and then just get the values ​​with Object.values(newObj)

const days = [
    {'name':'Mon','value':1}, 
    {'name':'Tue','value':5},
    {'name':'Wed','value':10},
    {'name':'Wed','value':30},
    {'name':'Fri','value':18},
    {'name':'Sat','value':80},
    {'name':'Sat','value':90},
    {'name':'Sun','value':20},
]

let res = {}
days.forEach(obj => {
    res = {...res, [obj.name]: [...(res[obj.name] || []), obj.value]}
})

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

Run code

Answer 3

Lodash groupBy map .

const days = [{"name":"Mon","value":1},{"name":"Tue","value":5},{"name":"Wed","value":10},{"name":"Wed","value":30},{"name":"Fri","value":18},{"name":"Sat","value":80},{"name":"Sat","value":90},{"name":"Sun","value":20}]

const result = _.chain(days)
  .groupBy('name')
  .values()
  .map(a => a.map(({value}) => value))
  
console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

Answer 4

Use Array # reduce to add names and values ​​to map . Then get a map of the iterator value and spread back to the array:

const days = [{"name":"Mon","value":1},{"name":"Tue","value":5},{"name":"Wed","value":10},{"name":"Wed","value":30},{"name":"Fri","value":18},{"name":"Sat","value":80},{"name":"Sat","value":90},{"name":"Sun","value":20}]

const result = [...days.reduce((m, { name, value }) => {
  m.has(name) || m.set(name, []) // if the name is not in the map, add a new key with an empty array

  m.get(name).push(value) // get the array for the name, and push the value 

  return m 
}, new Map).values()] // convert the Map back to an array

console.log(result)

Run code

Answer 5

You can use _. GroupBy , here's how you could do it.

 
const days = [
    { 'name': 'Mon', 'value': 1 },
    { 'name': 'Tue', 'value': 5 },
    { 'name': 'Wed', 'value': 10 },
    { 'name': 'Wed', 'value': 30 },
    { 'name': 'Fri', 'value': 18 },
    { 'name': 'Sat', 'value': 80 },
    { 'name': 'Sat', 'value': 90 },
    { 'name': 'Sun', 'value': 20 },
];

var t = _.groupBy(days, 'name');
result = [];
var s = Object.keys(t).forEach((i) => {
    var value = t[i];
    var temp = [];
    value.forEach((v) => {
        temp.push(v.value);
    });
    result.push(temp);
});

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

Run code