Question

我正在尝试使用Array.prototype.reduce（）

对数据进行分组

我按优先级分组，我的数据如下：

{ priorityId: 100, type: train color: black }
{ priorityId: 50, type: car, color: orange }
{ priorityId: 25, type: bike, color: yellow }
{ priorityId: 50, type: car, color: grey }
{ priorityId: 25 type: bike, color: white }
{ priorityId: 25, type: bike, color: green }

我按照此处发布的解决方案，分组工作完全正常： What is the most efficient method to groupby on a javascript array of objects?

var groupBy = function(xs, key) {
  return xs.reduce(function(rv, x) {
    (rv[x[key]] = rv[x[key]] || []).push(x);
    return rv;
  }, {});
};

我的分组现在看起来如下

groupedItems：

25:
 { priorityId: 25 type: bike, color: yellow }
{ priorityId: 25, type: bike, color: white }
{ priorityId: 25, type: bike, color: green}

50:
{ priorityId: 50, type: car, color: orange }
{ priorityId: 50, type: car, color: grey }

100:
{ priorityId: 100, type: train, color: black }

我最终希望将这些数据分组：

25: {
type: bike
colors: [yellow, white, green]
},
50:{
type: car
colors:[ orange, grey]
},
100:{
type: train
colors: [black]
}

我遇到的问题是我无法从减少的分组项目中迭代我的分组项目。这些项目显示为数组，但是长度为0，因此我无法映射以获得所需的最终分组。

如何进一步提取减少的分组项目以获得最终结果？

Answer 1

假设每个priorityId，只有一个type。

＆＃13;

function group(arr) {
    return arr.reduce(function(acc, o) {
        if(acc[o.priorityId])                                       // if we already encountered this priorityId before...
            acc[o.priorityId].colors.push(o.color);                 // then just add this object's color to the array colors of this priorityId objects
        else                                                        // otherwise (if we haven't encounter it yet)...
            acc[o.priorityId] = {type: o.type, colors: [o.color]};  // then create an object for it that has its type set to this object's type and its colors array containing (initially) this object's color
        return acc;
    }, {});
}


var data = [
    { priorityId: 100, type: "train", color: "black"  },
    { priorityId: 50,  type: "car",   color: "orange" },
    { priorityId: 25,  type: "bike",  color: "yellow" },
    { priorityId: 50,  type: "car",   color: "grey"   },
    { priorityId: 25,  type: "bike",  color: "white"  },
    { priorityId: 25,  type: "bike",  color: "green"  }
];

console.log(group(data));

＆＃13;

如何进一步将Array.prototype.reduce（）项目减少为新的子组

1 个答案: