json 如何将列表中的元素分组以形成新列表

628mspwn 于 2023-11-20 发布在其他

关注(0)|答案(4)|浏览(116)

我从我的API接收数据，如下所示：

[
  {grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1"},
  {grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1"},
  {grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1,  type: "Type_1"},
  {grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2"},
  {grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 26, type: "Type_2"}
]

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感谢StackOverflow的帖子，我成功地将我的列表转换为按类型对每个项目进行分组，如下所示：

var API_DATA = [
  {grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1"},
  {grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1"},
  {grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1,  type: "Type_1"},
  {grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2"},
  {grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 26, type: "Type_2"}
];

Array.prototype.groupBy = function(k) {
      return this.reduce((acc, item) => ((acc[item[k]] = [...(acc[item[k]] || []), item]), acc),{});
};

TABLE_DATA = API_DATA.groupBy("type")
console.log(TABLE_DATA)

型
不幸的是，我不能在Angular 材质mat-table的dataSource中使用这个结果，因为它不是一个列表：

Error: Provided data source did not match an array, Observable, or DataSource

型
如何检索由多个列表组成的列表：

[
  [
    {grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1"},
    {grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1"},
    {grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1,  type: "Type_1"}
  ],
  [
    {grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2"},
    {grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 26, type: "Type_2"}
  ]
]

型
谢谢你的帮助。

JSON

来源：https://stackoverflow.com/questions/63049234/how-to-group-the-elements-of-a-list-to-form-a-new-list

4条答案

按热度按时间

mpbci0fu1#

你可以从对象中得到值。

Array.prototype.groupBy = function(k) {
    return this.reduce((acc, item) => (acc[item[k]] = [...(acc[item[k]] || []), item], acc), {});
};

var API_DATA = [{ grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1" }, { grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1" }, { grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1,  type: "Type_1" }, { grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2" }, { grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 26, type: "Type_2" }],
    TABLE_DATA = Object.values(API_DATA.groupBy("type"));

console.log(TABLE_DATA);

个字符

2023年更新

新标准Object.groupBy：

const
    API_DATA = [{ grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1" }, { grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1" }, { grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1,  type: "Type_1" }, { grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2" }, { grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 26, type: "Type_2" }],
    TABLE_DATA = Object.values(Object.groupBy(API_DATA, ({ type }) => type));

console.log(TABLE_DATA);

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的字符串

赞(0）回复(0）举报 2023-11-20

igsr9ssn2#

您可以通过两种方式对这些数据进行分组。

第一种方法是分组到object
第二种方法是分组到array
Demo

注意：我使用JSON.stringify(group, null, 2) .来美化输出。

const API_DATA = [
    { grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1" },
    { grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1" },
    { grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1, type: "Type_1" },
    { grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2" },
    { grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 26, type: "Type_2" }
];

const groupBy = 'type';

console.log('------------------');
console.log('------Object------');
console.log('------------------');

const group1 = {};
for (let i = 0; i < API_DATA.length; i++) {
    const element = API_DATA[i];
    const groupByValue = element[groupBy];

    if (typeof group1[groupByValue] === 'undefined') {
        group1[groupByValue] = [element];
    } else {
        group1[groupByValue].push(element);
    }
}
console.log(JSON.stringify(group1, null, 2))



console.log('-------------------');
console.log('-------Array-------');
console.log('-------------------');

const group2 = [];
const tmp = {};
for (let i = 0; i < API_DATA.length; i++) {
    const element = API_DATA[i];
    const groupByValue = element[groupBy];

    if (typeof tmp[groupByValue] === 'undefined') {
        const position = group2.length; // get new position
        tmp[groupByValue] = position; // save it
        group2[position] = [element];
    } else {
        const position = tmp[groupByValue];
        group2[position].push(element);
    }
}
console.log(JSON.stringify(group2, null, 2))

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a1o7rhls3#

Array.prototype.groupBy = function (k) {
      return this.reduce(
        (acc, item) => ((acc[item[k]] = [...(acc[item[k]] || []), item]), acc),
        []
      );
    };

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neskvpey4#

可以在lodash上使用_.groupBy（）函数

var jsonArray = [
  {grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1"},
  {grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1"},
  {grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1,  type: "Type_1"},
  {grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2"},
  {grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 26, type: "Type_2"}
]

var groupJson= _.groupBy(jsonArray, function(jsonArray) {
  return jsonArray.type;
});

console.log(groupJson);

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json 如何将列表中的元素分组以形成新列表

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