javascript - 合并嵌套数组并对值求和

Question

我有以下格式的数据，

const data = [{
        key:'key1',
        rows:[
          ["A","2018","B","1"],
          ["A","2018","C","5"],
          ["A","2018","B","4"],
          ["A","2018","C","2"],
        ]
      },
      {
        key:'key1',
        rows:[
          ["A","2018","B","10"],
          ["A","2018","C","50"],
          ["A","2018","B","40"],
          ["A","2018","C","20"],
        ]
      }]

我想首先减少行并根据第三个值对每个数组中的最后一个值求和。输出应该是这样的，

const data = [{
        key:'key1',
        rows:[
          ["A","2018","B","5"],
          ["A","2018","C","7"]
        ]
      },
      {
        key:'key1',
        rows:[
          ["A","2018","B","50"],
          ["A","2018","C","70"]
        ]
      }]

此后，我想合并这两个对象并对行中的值求和。 最终输出应该是这样的，

const data = [{
        key:'key1',
        rows:[
          ["A","2018","B","55"],
          ["A","2018","C","77"]
        ]
      }]

我已经尝试过这个，但没有得到所需的输出，

data.map(data => ({
          ...data,
          rows: data.rows.reduce((array, value) => {
            if(array.length > 0){
              let found = false;
              array.map(m => {
                if(m[2] === value[2]){
                  found = true;
                  return [...m, m[3] = parseInt(m[3]) + parseInt(value[3])]
                }
              })
              if(!found){
                array.push(value)
              }
              return array
            }else{
              array.push(value)
              return array
            }
          }, [])
      }))

Answer 1

实现此目的的一种方法是迭代对象以获取行并将其展平，然后reduce数组以聚合它们，最后使用Object.values最后得到正确的数据集。

const data = [{ key: 'key1', rows: [ ["A", "2018", "B", "1"], ["A", "2018", "C", "5"], ["A", "2018", "B", "4"], ["A", "2018", "C", "2"] ] }, { key: 'key1', rows: [ ["A", "2018", "B", "10"], ["A", "2018", "C", "50"], ["A", "2018", "B", "40"], ["A", "2018", "C", "20"]]}];

const key = data[0].key;

// Use `flatMap` to iterate over the object and merge the rows
const merged = data.flatMap(el => el.rows);

const rows = Object.values(merged.reduce((acc, c) => {
  const [ k1, k2, k3, k4 ] = c;
  acc[k3] = acc[k3] || [ k1, k2, k3, 0 ];
  acc[k3][3] += +k4;
  return acc;
}, {}));

console.log([{ key, rows }]);

注意:如果您需要返回字符串的聚合数字，只需映射结果即可:

.map(([ a, b, c, d ]) => {
  return [ a, b, c, d.toString() ];
});

进一步阅读

• flatMap
• reduce
• Object.values