如何在javascript中分组或合并此对象数组？

Question

I have an array of objects like below for example.

{name: "Mc Donald", quantity: 4, maleCount: 1, femaleCount: 0}
{name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}
{name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}
{name: "Mc Donald", quantity: 4, maleCount: 0, femaleCount: 1}
{name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}
{name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}
{name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}
{name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}

I want to group them up and adding up all the values in it. For example, the final would be like this:

{name: "Mc Donald", quantity: 8, maleCount: 1, femaleCount: 1}
{name: "KFC", quantity: 54, maleCount: 3, femaleCount: 3}

How can I achieve this in JavaScript?

I have tried to find some solution online but it is not the one I wanted. For example this solution

Answer 1

You can use array reduce:

 var arr = [ {name: "Mc Donald", quantity: 4, maleCount: 1, femaleCount: 0}, {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}, {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}, {name: "Mc Donald", quantity: 4, maleCount: 0, femaleCount: 1}, {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}, {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}, {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}, {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1} ]; var finalArr = arr.reduce((m, o) => { var found = m.find(p => p.name === o.name); if (found) { found.quantity += o.quantity; found.maleCount += o.maleCount; found.femaleCount += o.femaleCount; } else { m.push(o); } return m; }, []); console.log(finalArr); 

Answer 2

You can use forEach() loop and add to new array. You can pass empty object as thisArg parameter that you can use as this in your callback function and in second forEach context of this will still be the same as in first callback function because of arrow function.

 var data = [{"name":"Mc Donald","quantity":4,"maleCount":1,"femaleCount":0},{"name":"KFC","quantity":9,"maleCount":1,"femaleCount":0},{"name":"KFC","quantity":9,"maleCount":1,"femaleCount":0},{"name":"Mc Donald","quantity":4,"maleCount":0,"femaleCount":1},{"name":"KFC","quantity":9,"maleCount":0,"femaleCount":1},{"name":"KFC","quantity":9,"maleCount":1,"femaleCount":0},{"name":"KFC","quantity":9,"maleCount":0,"femaleCount":1},{"name":"KFC","quantity":9,"maleCount":0,"femaleCount":1}] var result = [], keys = ['quantity', 'maleCount', 'femaleCount'] data.forEach(function(e) { if(!this[e.name]) result.push(this[e.name] = e); else keys.forEach(k => this[e.name][k] += e[k]) }, {}) console.log(result) 

Answer 3

You could group with a hash table and use an array for the keys with variable values.

 var array = [{ name: "Mc Donald", quantity: 4, maleCount: 1, femaleCount: 0 }, { name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0 }, { name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0 }, { name: "Mc Donald", quantity: 4, maleCount: 0, femaleCount: 1 }, { name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1 }, { name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0 }, { name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1 }, { name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1 }], groups = Object.create(null), result = array.reduce(function (r, o) { var values = ['quantity', 'maleCount', 'femaleCount']; if (!groups[o.name]) { groups[o.name] = { name: o.name }; r.push(groups[o.name]); values.forEach(function (k) { groups[o.name][k] = 0; }); } values.forEach(function (k) { groups[o.name][k] += o[k]; }); return r; }, []); console.log(result); 

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

With linq.js

 var array = [{ name: "Mc Donald", quantity: 4, maleCount: 1, femaleCount: 0 }, { name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0 }, { name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0 }, { name: "Mc Donald", quantity: 4, maleCount: 0, femaleCount: 1 }, { name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1 }, { name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0 }, { name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1 }, { name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1 }], result = Enumerable.From(array) .GroupBy( "$.name", null, "{ name: $.Key, quantity: $$.Sum('$.quantity'), maleCount: $$.Sum('$.maleCount'), femaleCount: $$.Sum('$.femaleCount') }" ) .ToArray(); console.log(result); 

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

 <script src="https://cdnjs.cloudflare.com/ajax/libs/linq.js/2.2.0.2/linq.js"></script> 

Answer 4

My solution based on reduce:

 let data = [ {name: "Mc Donald", quantity: 4, maleCount: 1, femaleCount: 0}, {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}, {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}, {name: "Mc Donald", quantity: 4, maleCount: 0, femaleCount: 1}, {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}, {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}, {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}, {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1} ]; // We will only keep an array of values of the merged object let result = Object.values( // Merge data to name indexed objects data.reduce((p,c) => { // Ensure key (name) exists if (!p[c.name]) { // If first occurence, duplicate object (to avoid modification of original array) p[c.name] = Object.assign({}, c); } else { // If key (name) already exists, sum up relevant attributes p[c.name].quantity += c.quantity; p[c.name].maleCount += c.maleCount; p[c.name].femaleCount += c.femaleCount; } // return updated object return p; }, {}) ); console.log(result); 

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

hope this will help

Answer 5

More functional/universal approach

 const normalizeValue = (value) => value === undefined ? 0 : value const sumUpProps = (props = []) => (a = {}, b = {}) => { const result = {} props.forEach((prop) => { result[prop] = normalizeValue(a[prop]) + normalizeValue(b[prop]) }) return result } const data = [ {name: "Mc Donald", quantity: 4, maleCount: 1, femaleCount: 0}, {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}, {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}, {name: "Mc Donald", quantity: 4, maleCount: 0, femaleCount: 1}, {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}, {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0}, {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}, {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1} ] const entries = {} const sumObjects = sumUpProps(['quantity', 'maleCount', 'femaleCount']) data.forEach((item) => { const entry = entries[item.name] || {} entries[item.name] = sumObjects(entry, item) }) console.log(entries) 

Answer 6

check this code below:

var array = [
    {name: "Mc Donald", quantity: 4, maleCount: 1, femaleCount: 0},
    {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0},
    {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0},
    {name: "Mc Donald", quantity: 4, maleCount: 0, femaleCount: 1},
    {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1},
    {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0},
    {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1},
    {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1},
];

var result = [];

for(var index in array){
    var obj = array[index];
    if(result.hasOwnProperty(obj.name)) {
        result[obj.name].quantity += obj.quantity;
        result[obj.name].maleCount += obj.maleCount;
        result[obj.name].femaleCount += obj.femaleCount;
    }else{
        result[obj.name] = {};
        result[obj.name].quantity = obj.quantity;
        result[obj.name].maleCount = obj.maleCount;
        result[obj.name].femaleCount = obj.femaleCount;
    }
}

console.log(result);

Answer 7

Here is a generic solution that uses clean and modern JavaScript:

 function groupRestaurants(restaurants) { const groups = new Map(); restaurants.forEach(restaurant => { const group = findOrCreateGroup(groups, restaurant.name); addRestaurantToGroup(group, restaurant); }); return [...groups.values()]; } function findOrCreateGroup(groups, name) { let group = groups.get(name); if (!group) { group = { name }; groups.set(name, group); } return group; } function addRestaurantToGroup(group, restaurant) { for (const [key, value] of Object.entries(restaurant)) { if (key !== 'name') { if (group.hasOwnProperty(key)) { group[key] += value; } else { group[key] = value; } } } } const restaurants = [ { name: "Mc Donald", quantity: 4, maleCount: 1, femaleCount: 0 }, { name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0 }, { name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0 }, { name: "Mc Donald", quantity: 4, maleCount: 0, femaleCount: 1 }, { name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1 }, { name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0 }, { name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1 }, { name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1 } ]; console.log(groupRestaurants(restaurants)); 

Answer 8

Lodash makes your life easy.

_.map(_.groupBy(yourArrayHere, 'name'), (groupMembers, groupKey) => {
    let sumObject = {name: groupKey};

    _.forEach(['quantity', 'maleCount', 'femaleCount'], (property) => {
        sumObject[property] = 0;
        _.forEach(groupMembers, (member) => {
            sumObject[property] += member[property];
        });
    });

    return sumObject;
});