使用 Ramda 减少对象数组

Question

I have an array of array of objects. I want to reduce that to an array of object and adding one more property to each object. The sample input is:

const data = [
    [
        {name:"a", val:5},
        {name:"b", val:10},
        {name:"c", val:20},
        {name:"d", val:50},
        {name:"e", val:100}
    ],
    [
        {name:"a", val:0},
        {name:"b", val:20},
        {name:"c", val:30},
        {name:"d", val:40},
        {name:"e", val:10}
    ],
    [
        {name:"a", val:60},
        {name:"b", val:50},
        {name:"c", val:40},
        {name:"d", val:70},
        {name:"e", val:30}
    ]
];

And the Output should be:

[{name: 'a', val: 65, rank: 'si'},
 {name: 'b', val: 80, rank: 'dp'},
 {name: 'c', val: 90, rank: 'en'}
 {name: 'd', val: 160, rank: 'fr'}]

Rank is static text means for a , it will always be "si" How can I achieve this using ramda ?

Answer 1

You can convert flatten all sub arrays to a single array, group by the name , and then map the groups, and reduce each group to a single object using R.mergeWithKey to add the val property. Convert back to an array using R.values, and map to add the static ranks property by name .

Note that you must create a Map or a dictionary object to take the rank by name from.

 const { mergeWithKey, pipe, flatten, groupBy, prop, map, reduce, values } = R const ranks = new Map([['a', 'si'], ['b', 'dp'], ['c', 'en'], ['d', 'fr']]) // merge deep and combine val property values const combine = mergeWithKey((k, l, r) => k == 'val'? l + r: r) const mergeData = pipe( flatten, // flatten to a single array groupBy(prop('name')), // group by the name map(reduce(combine, {})), // combine each group to a single object values, // convert back to array map(o => ({...o, rank: ranks.get(o.name) })), // add the static rank property ) const data = [[{"name":"a","val":5},{"name":"b","val":10},{"name":"c","val":20},{"name":"d","val":50},{"name":"e","val":100}],[{"name":"a","val":0},{"name":"b","val":20},{"name":"c","val":30},{"name":"d","val":40},{"name":"e","val":10}],[{"name":"a","val":60},{"name":"b","val":50},{"name":"c","val":40},{"name":"d","val":70},{"name":"e","val":30}]] const results = mergeData(data) console.log(results)

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