我试图根据两个属性组合两个对象数组,并重写连接数据集中其他属性的名称。
数据集如下所示:
var xData = [
{ row_id: 1, date: '2013-04-01', cost: 18 },
{ row_id: 2, date: '2013-04-01', cost: 27 } ...
];
var yData = [
{ row_id: 1, date: '2013-04-01', cost: 48 },
{ row_id: 3, date: '2013-04-01', cost: 37 } ...
];
我想要加入的属性是 row_id
和date
属性,我想重写 cost
至x_cost
和y_cost
分别。我还想处理缺失值。这就是我想要的结果:
var combinedData = [
{ row_id: 1, date: '2013-04-01', x_cost: 18, y_cost: 48 },
{ row_id: 2, date: '2013-04-01', x_cost: 27, y_cost: null },
{ row_id: 3, date: '2013-04-01', x_cost: null, y_cost: 37 } ...
];
这是我现在的代码。这太可怕了:
combineXAndYDatasets: function(xData, yData) {
// Index both datasets by ID and date.
var x_indexed_by_id_and_date = {};
xData.forEach(function(d) {
var k = d.row_id + '_' + d.date;
x_indexed_by_id_and_date[k] = d;
});
var y_indexed_by_id_and_date = {};
yData.forEach(function(d) {
var k = d.row_id + '_' + d.date;
y_indexed_by_id_and_date[k] = d;
});
var combinedData = [];
// Iterate over ydata, join with xdata if possible.
for (var row_id in y_indexed_by_id_and_date) {
var row = JSON.parse(JSON.stringify(y_indexed_by_id_and_date[row_id]));
row.y_cost = +y_indexed_by_id_and_date[row_id].cost;
if (row_id in x_indexed_by_id_and_date) {
row.x_cost = +x_indexed_by_id_and_date[row_id].cost;
} else {
row.x_cost = null;
}
combinedData.push(row);
}
// Iterate over xdata, add anything that wasn't in ydata.
for (var x_row_id in x_indexed_by_id_and_date) {
if (!(x_row_id in y_indexed_by_id_and_date)) {
var x_row = JSON.parse(JSON.stringify(x_indexed_by_id_and_date[x_row_id]));
x_row.y = null;
x_row.x = +x_row.cost;
combinedData.push(x_row);
}
}
return combinedData;
}
我能做些什么来让这件事不那么糟糕?
我正在使用 jQuery,我可以添加例如划线是否有帮助。
最佳答案
您可以利用 reduce
将每个数组缩减为字典,然后将该字典转换回数组。像这样的东西(vanilla JS,不是开箱即用的 IE 8 兼容):
var xData = [
{ row_id: 1, date: '2013-04-01', cost: 18 },
{ row_id: 2, date: '2013-04-01', cost: 27 }
];
var yData = [
{ row_id: 1, date: '2013-04-01', cost: 48 },
{ row_id: 3, date: '2013-04-01', cost: 37 }
];
var xDataDict = xData.reduce(function(p,c) {
createDictionaryEntry(p,c,c.cost,null)
return p;
},{});
xAndYDataDict = yData.reduce(function(p,c) {
createDictionaryEntry(p,c,null,c.cost)
return p;
}, xDataDict);
var combinedData = Object.keys(xAndYDataDict).map(function(key) {
return xAndYDataDict[key];
});
alert(JSON.stringify(combinedData));
function createDictionaryEntry(p,c,x_cost,y_cost) {
var key = c.row_id + "-" + c.date;
if (p[key]) {
p[key].x_cost = p[key].x_cost || x_cost;
p[key].y_cost = p[key].y_cost || y_cost;
} else {
p[key] = {
row_id: c.row_id,
date: c.date,
x_cost: x_cost,
y_cost: y_cost
}
}
}
请注意,combinedData
不会按任何保证的顺序排列,因此,如果这很重要,您可以随时对其进行排序
。
使用下划线:
var xData = [
{ row_id: 1, date: '2013-04-01', cost: 18 },
{ row_id: 2, date: '2013-04-01', cost: 27 }
];
var yData = [
{ row_id: 1, date: '2013-04-01', cost: 48 },
{ row_id: 3, date: '2013-04-01', cost: 37 }
];
var xDataDict = _.reduce(xData, function(p,c) {
createDictionaryEntry(p,c,c.cost,null)
return p;
},{});
xAndYDataDict = _.reduce(yData,function(p,c) {
createDictionaryEntry(p,c,null,c.cost)
return p;
}, xDataDict);
var combinedData = _.map(Object.keys(xAndYDataDict),function(key) {
return xAndYDataDict[key];
});
alert(JSON.stringify(combinedData));
function createDictionaryEntry(p,c,x_cost,y_cost) {
var key = c.row_id + "-" + c.date;
if (p[key]) {
p[key].x_cost = p[key].x_cost || x_cost;
p[key].y_cost = p[key].y_cost || y_cost;
} else {
p[key] = {
row_id: c.row_id,
date: c.date,
x_cost: x_cost,
y_cost: y_cost
}
}
}
<script src="//cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
关于javascript - 在两个属性上连接两个对象数组的更好方法?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31319770/