How to ReMap an array of object into new array

user_3614378 0
Viewed 196

I have this initial array:

const initialData = [
  {
    day: 1,
    values: [
      {
        name: 'Roger',
        score: 90,
      },
      {
        name: 'Kevin',
        score: 88,
      },
      {
        name: 'Steve',
        score: 80,
      },
    ],
  },
  {
    day: 2,
    values: [
      {
        name: 'Roger',
        score: 70,
      },
      {
        name: 'Michael',
        score: 88,
      },
    ],
  },
  {
    day: 3,
    values: [
      {
        name: 'Steve',
        score: 97,
      },
    ],
  },
];

to be converted into:

const result = [
  {
    name: 'Roger',
    scores: [90, 70, null],
  },
  {
    name: 'Kevin',
    scores: [88, null, null],
  },
  {
    name: 'Steve',
    scores: [80, null, 97],
  },
  {
    name: 'Michael',
    scores: [null, 88, null],
  },
];

I'm trying to use array map and create temporary array:

const holder = [];

initialData.map()

but to no avail

typescript ecmascript-6 javascript
2 Answers

You can do this in a couple of steps - first reduce so you can index by name, and then map those entries to the format you expected

const initialData = [{day:1,values:[{name:"Roger",score:90},{name:"Kevin",score:88},{name:"Steve",score:80}]},{day:2,values:[{name:"Roger",score:70},{name:"Michael",score:88}]},{day:3,values:[{name:"Steve",score:97}]}];


var result = Object.entries(initialData.reduce( (acc,item) => {
  item.values.forEach( v => {
    if(!acc[v.name]) acc[v.name] = {};
    acc[v.name][item.day] = v.score;
  });
  return acc;
},{})).map( ([name,days]) => ({  
    name,
    scores: new Array(initialData.length).fill(null).map( (_,i) => days[i+1] || null)
}))

console.log(result);

user_2196610

You could use reduce and forEach to create one object for each name and then to get an array from that object you can just use Object.values method.

const data = [{"day":1,"values":[{"name":"Roger","score":90},{"name":"Kevin","score":88},{"name":"Steve","score":80}]},{"day":2,"values":[{"name":"Roger","score":70},{"name":"Michael","score":88}]},{"day":3,"values":[{"name":"Steve","score":97}]}]

const obj = data.reduce((r, { values }, i) => {
  values.forEach(({ name, score }) => {
    if (!r[name]) r[name] = { name, scores: Array(data.length).fill(null)}
    r[name].scores[i] = score
  })
  
  return r;
}, {})

const result = Object.values(obj)

console.log(result)

user_46207710
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