按数组中的多个属性分组

Question

通过多个属性对数组进行分组，我能够使用单个属性进行分组，但我无法使用 2 个属性获得正确的输出

我有一个这样的数组

var grouping=
    [
     {
        name: "Micheal", 
        branch: "arts",
        school: "little star"
      },
      {
        name: "james", 
        branch: "science",
        school: "little flower"
      },
      {
        name: "Harry", 
        branch: "arts",
        school: "little star"
      },
      {
        name: "emma", 
        branch: "science",
        school: "little flower"
      },
      {
        name: "Schmitt,", 
        branch: "zoology",
        school: "Buds And Flowers High School"
      },
      {
        name: "Tobias,", 
        branch: "biology",
        school: "Boarding School"
      }
    ]

我想分组（分行、学校）输出应该是

[
  [
    {
    name: "Micheal", 
    branch: "arts",
    school: "little star"
    },
   {
    name: "Harry", 
    branch: "arts",
    school: "little star"
   }
 ], 
  [
   {
    name: "james", 
    branch: "science",
    school: "little flower"
   },
   {
    name: "emma", 
    branch: "science",
    school: "little flowe"
   }
  ],
   {
    name: "Schmitt,", 
    branch: "zoology",
    school: "Buds And Flowers High School"
  },
  {
    name: "Tobias,", 
    branch: "biology",
    school: "Boarding School"
  }
]

iam 能够使用下面代码中的单个属性（分支）成功进行分组分组=上面的数组

var hash = Object.create(null),
        result = [];

      this.grouping.forEach(function (a) {
        if (!hash[a['branch']] ) {
          hash[a['branch']] = [];
          result.push(hash[a['branch']]);
        }
        hash[a['branch']].push(a);
      }); 
      console.log( result)

任何帮助将不胜感激

谢谢

Answer 1

按数组索引分组可能不是理想的未来证明。我建议按键分组，然后您可以通过引用键简单地提取整个对象。

像这样

let all_data = [{
    name: "Micheal",
    branch: "arts",
    school: "little star"
  },
  {
    name: "james",
    branch: "science",
    school: "little flower"
  },
  {
    name: "Harry",
    branch: "arts",
    school: "little star"
  },
  {
    name: "emma",
    branch: "science",
    school: "little flower"
  }
];

let items = groupBy(all_data, 'branch')
for (let branch in items)
  items[branch] = groupBy(items[branch], 'school')

console.log(JSON.stringify(items))

//{
//  "arts": {
//     "little star":[
//         { "name":"Micheal", "branch":"arts", "school":"little star" }, 
//         { "name":"Harry", "branch":"arts", "school":"little star" }
//      ]
//   },
//   "science": {
//      "little flower":[
//         { "name":"james", "branch":"science", "school":"little flower" }, 
//         { "name":"emma", "branch":"science", "school":"little flower"}
//      ]
//   }
//}

//group an array of objects into an object by object key
function groupBy(objectArray, property) {
  return objectArray.reduce((acc, obj) => {
    if (!acc[obj[property]])
      acc[obj[property]] = [];
    acc[obj[property]].push(obj);
    return acc;
  }, {});
}

Answer 2

您可以生成所需组的组合键并从收集对象中获取值。

var data = [{ name: "Micheal",  branch: "arts", school: "great star" }, { name: "james",  branch: "science", school: "little flower" }, { name: "Harry",  branch: "arts", school: "little star"  }, { name: "emma",  branch: "science",  school: "little flower" }, { name: "Schmitt,", branch: "zoology", school: "Buds And Flowers High School" }, { name: "Tobias,",  branch: "biology", school: "Boarding School" }],
    groups = ['branch', 'school'],
    result = Object.values(data.reduce((r, o) => {
        const key = groups.map(k => o[k]).join('|');
        (r[key] ??= []).push(o);
        return r;
    }, {}));

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 3

当值为 1 时添加了 if 标志。该值是通过过滤函数找到的，该函数找到一个没有相同值的值。找到值后，将单独的值推送到结果数组。

/*
[
  [
    {
    name: "Micheal", 
    branch: "arts",
    school: "little star"
    },
   {
    name: "Harry", 
    branch: "arts",
    school: "little star"
   }
 ], 
  [
   {
    name: "james", 
    branch: "science",
    school: "little flower"
   },
   {
    name: "emma", 
    branch: "science",
    school: "little flowe"
   }
  ],
   {
    name: "Schmitt,", 
    branch: "zoology",
    school: "Buds And Flowers High School"
  },
  {
    name: "Tobias,", 
    branch: "biology",
    school: "Boarding School"
  }
]
*/
var grouping=
    [
     {
        name: "Micheal", 
        branch: "arts",
        school: "little star"
      },
      {
        name: "james", 
        branch: "science",
        school: "little flower"
      },
      {
        name: "Harry", 
        branch: "arts",
        school: "little star"
      },
      {
        name: "emma", 
        branch: "science",
        school: "little flower"
      },
      {
        name: "Schmitt,", 
        branch: "zoology",
        school: "Buds And Flowers High School"
      },
      {
        name: "Tobias,", 
        branch: "biology",
        school: "Boarding School"
      }
    ]
    
var hash = Object.create(null),
        result = [];

      this.grouping.forEach(function (a) {      
      
      //this filter to find solo value.
      let solo = grouping.filter((one) => one.branch === a.branch).length;        
      let sortBySchool = grouping.filter((one) => one.school === a.school).length;
      //this filter to find a value which have 2 conditions.
      let sortBy2Condition = grouping.filter((one) => 
      one.school === a.school && one.branch === a.branch
      ).length;
      
      //if only value then just push to result arry.
        if (solo === 1) {                  
          result.push(a);
        } else {
        if (!hash[a['branch']] ) {
          hash[a['branch']] = [];
          result.push(hash[a['branch']]);
        }
        hash[a['branch']].push(a);
      }
      }); 
      
      console.log( result)

按数组中的多个属性分组

Group by multiple properties in a array

javascript

arrays

reduce

grouping

object