通过汇总相同元素来进行JavaScript数组排序

Question

尝试对JavaScript中的数组项进行排序和分组时遇到了麻烦。 这是示例输入：

var arr = [
{merchantName: '', branchName: 'e', branchAddress: '', total: 10.5},
];

我正在尝试实现的输出：

var arr = [
{merchantName: '', branchName: '', branchAddress: '', total: 10.5},
];

我想按branchName对其进行排序，例如，将相同branchName的总数求和，然后同时将所有其他属性（例如商人名称和branchAddress）与其绑定在一起，以便我可以像这样访问它们：

for(var i = 0; i < arr.length; i++){
            console.log(arr[i].merchantName + ' ' + arr[i].branchName + ' ' + arr[i].branchAddress + ' ' + arr[i].total);
        }

实际上，我什至不知道如何启动它。 有什么想法要实现吗？

提前致谢！

Answer 1

所以这是我要怎么做：

1. 根据branchName属性将数组分组为一个hashmap branchName -连同它一起计算总数。

2. 从hashmap取出数组并对它们进行排序

请参见下面的演示：

 var arr = [ {merchantName: 'Giant', branchName: 'Giant Marine', branchAddress: 'Terrace 56 Branch Blk 56 Marine Terrace #01-259/261 Singapore 440056', total: 10.5}, {merchantName: 'Ntuc', branchName: 'Ntuc Zhongshan Mall Branch', branchAddress: ' Zhongshan Mall Balestier #02-01, 20 Ah Hood Road, 329984', total: 12.149999999999999}, {merchantName: 'Giant', branchName: 'Giant Kim Keat 260 Branch', branchAddress: ' Blk 260 Kim Keat Avenue #01-01 Singapore 310260', total: 5.1}, {merchantName: 'Ntuc', branchName: 'Ntuc Scotts Square Branch', branchAddress: ' Scotts Square #B1-03 To 07 & #B1-10, 6 Scotts Road, 228209', total: 4}, {merchantName: 'Ntuc', branchName: 'Ntuc Zhongshan Mall Branch', branchAddress: ' Zhongshan Mall Balestier #02-01, 20 Ah Hood Road, 329984', total: 4}, {merchantName: 'Ntuc', branchName: 'Ntuc Zhongshan Mall Branch', branchAddress: ' Zhongshan Mall Balestier #02-01, 20 Ah Hood Road, 329984', total: 8} ]; // create a hashmap var hash = arr.reduce(function(p,c){ if(!p[c.branchName]) p[c.branchName] = c; else p[c.branchName].total += c.total; return p; }, Object.create(null)) // now extract the result and sort them var result = Object.keys(hash).map(function(e){ return hash[e]; }).sort(function(a,b){ return a.branchName - b.branchName; }); console.log(result); 

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

Answer 2

使用reduce()解决方案

 var arr = [{ merchantName: 'Giant', branchName: 'Giant Marine', branchAddress: 'Terrace 56 Branch Blk 56 Marine Terrace #01-259/261 Singapore 440056', total: 10.5 }, { merchantName: 'Ntuc', branchName: 'Ntuc Zhongshan Mall Branch', branchAddress: ' Zhongshan Mall Balestier #02-01, 20 Ah Hood Road, 329984', total: 12.149999999999999 }, { merchantName: 'Giant', branchName: 'Giant Kim Keat 260 Branch', branchAddress: ' Blk 260 Kim Keat Avenue #01-01 Singapore 310260', total: 5.1 }, { merchantName: 'Ntuc', branchName: 'Ntuc Scotts Square Branch', branchAddress: ' Scotts Square #B1-03 To 07 & #B1-10, 6 Scotts Road, 228209', total: 4 }, { merchantName: 'Ntuc', branchName: 'Ntuc Zhongshan Mall Branch', branchAddress: ' Zhongshan Mall Balestier #02-01, 20 Ah Hood Road, 329984', total: 4 }, { merchantName: 'Ntuc', branchName: 'Ntuc Zhongshan Mall Branch', branchAddress: ' Zhongshan Mall Balestier #02-01, 20 Ah Hood Road, 329984', total: 8 } ]; var newArr = arr.reduce(function(items, item) { var existing = items.find(function(i) { return i.branchName === item.branchName; }); if (existing) { existing.total += item.total; } else { items.push(item); } return items; }, []); console.log(newArr); 

Answer 3

看起来您想做两件事：按branchName排序，然后为每个branchName输出一个值（对结果进行重复数据删除/按branchName分组）。

有两个潜在的问题。 1）上面显示的示例输出未按branchName进行排序，即使您声明a）您希望按branchName对其进行排序，b）这将是一个示例。 其次，输出并不完全是确定性的-特别是您似乎只是输出第一个匹配的记录形式branchName，因此显示了total属性的值-在同一branchName的记录之间有所不同。 所以...假设您A）希望对结果进行排序，而B）不在乎“总计”属性的值，则可以通过以下方法轻松完成此操作：

我）排序数组。 有关示例，请参见https://gist.github.com/umidjons/9614157 ：只需编写一个用于比较branchName值的比较函数。 并且，II）遍历结果，每当branchName从先前的值更改时，仅输出第一条记录。