javascript - UnderscoreJS 对象组列表

Question

我有一个来自数据库的对象数组，为了简洁起见，我想将其折叠。我已导入 underscore.js 来帮助完成此过程，但尝试使用提供的“groupBy”函数来压缩以下列表未成功:

[
    {ID:2570,name:"jim",latitude:59.4,longitude:-7.29},
    {ID:2573,name:"joe",latitude:54.4,longitude:-7.36},
    {ID:2573,name:"joe",latitude:54.3,longitude:-7.37},
    {ID:2574,name:"bob",latitude:58.4,longitude:-7.31},
    {ID:2574,name:"bob",latitude:58.6,longitude:-7.38},
    {ID:2574,name:"bob",latitude:58.8,longitude:-7.39},
    {ID:2575,name:"mary",latitude:54.1,longitude:-7.30},
]

格式:

[
    {ID:2570, name:"jim", locs : [[59.4,-7.29]]},
    {ID:2573, name:"joe", locs : [[54.4,-7.36], [54.3,-7.37]]} //etc...
]

Answer 1

按照您的直觉使用_.groupBy，

var data = [
    {ID:2570,name:"jim",latitude:59.4,longitude:-7.29},
    {ID:2573,name:"joe",latitude:54.4,longitude:-7.36},
    {ID:2573,name:"joe",latitude:54.3,longitude:-7.37},
    {ID:2574,name:"bob",latitude:58.4,longitude:-7.31},
    {ID:2574,name:"bob",latitude:58.6,longitude:-7.38},
    {ID:2574,name:"bob",latitude:58.8,longitude:-7.39},
    {ID:2575,name:"mary",latitude:54.1,longitude:-7.30},
];
    
var groups = _.groupBy(data, function(locationObject) { return locationObject.ID; });
    
var result = _.map(groups, function(group) {
    var condensed = {ID: group[0].ID, name: group[0].name};
    condensed.locs = _.map(group, function(row) { 
        return [row.latitude, row.longitude]; 
    }); 
    return condensed;
});

document.getElementById('log').innerHTML = JSON.stringify(result, null, '  ');

<script src="http://underscorejs.org/underscore-min.js"></script>
<pre id="log"></pre>