javascript - 通过计算将对象数组转换为数组

Question

我正在使用以下对象数组并尝试将其转换为数组:

const data = [
  {
    count: 3,
    userName: "Paul Crewe",
    value: "Activity Type",
  },
  {
    count: 1,
    userName: "Nate Scarborough",
    value: "Activity Type",
  },
  {
    count: 1,
    userName: "Nate Scarborough",
    value: "Another Activity Type",
  },
  {
    count: 1,
    userName: "Paul Crewe",
    value: "Another Activity Type",
  },
];

预期结果:

const outcome = [
  ['userName', 'Paul Crewe', 'Nate Scarborough'],
  ['Activity Type', 3, 1],
  ['Another Activity Type', 1, 1]
];

结果数组获取数据并使用 userName 键创建第一个数组元素，后跟 value 格式，count 为每个额外的数组元素。例如，

['userName', 'Paul Crewe', 'Nate Scarborough'],
[{value}, {count for Paul Crewe}, {count for Nate Scarborough} ],

我觉得使用reduce 是合适的并且已经开始:

data.reduce((a, c) => {
  a[c.userName] = { value: c.value, count: c.count };
  a[c.userName].count += c.count;
  return a;
}, {});

但这会导致不希望的结果，例如:

{
  Nate Scarborough: {value: "Another Activity Type", count: 2},
  Paul Crewe: {value: "Another Activity Type", count: 2},
}

Answer 1

您可以从键 userName 开始，然后根据需要构建新的值行。它适用于任意数量的值。

这个解决方案可以返回一个稀疏数组。如果不需要，则需要使用默认零映射内部数组。

const
    data = [{ count: 3, userName: "Paul Crewe", value: "Activity Type" }, { count: 1, userName: "Nate Scarborough", value: "Activity Type" }, { count: 1, userName: "Nate Scarborough", value: "Another Activity Type" }, { count: 1, userName: "Paul Crewe", value: "Another Activity Type" }],
    result = data.reduce((r, o) => {
        var vIndex = r.findIndex(([v]) => v === o.value),
            index = r[0].indexOf(o[r[0][0]]);

        if (vIndex < 0) {
            vIndex += r.push([o.value]);
        }            
        if (index < 0) {
            index += r[0].push(o[r[0][0]]);             
        }
        r[vIndex][index] = (r[vIndex][index] || 0) + o.count;
        return r;
    }, [['userName']]);

console.log(result);

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