Question

我有一个数组，我希望获得唯一的值和它们的出现次数，并总结匹配的公司名称。我正在使用lodash，到目前为止我能够获得每个独特的价值。

如何有效地获取每次出现的次数，并将它们相加？价格数据是字符串。

"typescript": ^2.0.0"

我需要的结果：

var data = [
 {"cat":"IT","company":"Apple", "price":"100.5"},
 {"cat":"IT","company":"Apple", "price":"100"},
 {"cat":"IT","company":"Google", "price": "100"},
 {"cat":"IT","company":"Apple", "price": "100"}
];

到目前为止我的代码：

Company | Count | Sum
Apple   |   3   | 300.5
Google  |   1   | 100

是否可以在同一个_.map函数中进行求和？

Answer 1

您可以先groupBy公司，然后map和reduce返回每家公司的对象数组。

var data = [
 {"cat":"IT","company":"Apple", "price":"100.5"},
 {"cat":"IT","company":"Apple", "price":"100"},
 {"cat":"IT","company":"Google", "price": "100"},
 {"cat":"IT","company":"Apple", "price": "100"}
];

var group = _.groupBy(data, 'company')

var result = _.map(_.keys(group), function(e) {
  return _.reduce(group[e], function(r, o) {
    return r.count += +o.price, r
  }, {Company: e, count: 0, sum: group[e].length})
})

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.15.0/lodash.min.js"></script>

Answer 2

使用Array.prototype.reduce()和Object.keys()函数的

纯JS （ Ecmascript5 ）解决方案：

var data = [
 {"cat":"IT","company":"Apple", "price":"100.5"},
 {"cat":"IT","company":"Apple", "price":"100"},
 {"cat":"IT","company":"Google", "price": "100"},
 {"cat":"IT","company":"Apple", "price": "100"}
], rows = "";

var result = data.reduce(function(r, o) {
    if (r[o.company]){
        ++r[o.company].count;
        r[o.company].price += Number(o.price);
    } else {
        r[o.company] = {count: 1, price: Number(o.price)};
    }
    return r;
}, {});

Object.keys(result).forEach(function(name){
  rows += '<tr><td>'+ name +'</td>' + 
          '<td>'+ result[name].count +'</td>' +
          '<td>'+ result[name].price +'</td></tr>';

});
$('table').append(rows);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<table>
  <tr>
    <th>Company</th>
    <th>Count</th>
    <th>Sum</th>
  </tr>        
</table>

使用lodash从数组中获取唯一值，总和和计数

2 个答案: