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我在使用 d3js 和日期时遇到了一些麻烦：

这是一些数据，带有重量和日期的对象数组

var weights = [{"atdate":"2013-09-07","weight":"82","comment":"Reprise !"},
{"atdate":"2013-09-10","weight":"81.3","comment":""},
{"atdate":"2013-09-15","weight":"80.8","comment":""},
{"atdate":"2013-09-16","weight":"80.8","comment":""},
{"atdate":"2013-09-17","weight":"80.3","comment":""},
{"atdate":"2013-09-18","weight":"81.2","comment":""},
{"atdate":"2013-09-19","weight":"80.9","comment":""},
{"atdate":"2013-09-20","weight":"80.7","comment":""},
{"atdate":"2013-09-21","weight":"81","comment":""},
{"atdate":"2013-09-22","weight":"80.8","comment":""}];

可以看到最小日期是 2013-09-07，最大日期是 2013-09-22

现在，我将这些数据发送到一个函数

function draw_spline (_weights) {

    var parse_date = d3.time.format('%Y-%m-%d').parse;
    var weights = _weights.map(function(w) {
        w.atdate = parse_date(w.atdate);
        w.weight = parseFloat(w.weight);
        return w;
    })

    var x = d3.time.scale().range([0,width]);

    var boundaries_dates = d3.extent(weights, function(d){return d.atdate});
    console.log('boundaries_dates',boundaries_dates);
    x.domain(boundaries_dates);
    console.log('domain extent',x.domain());

    ...

我使用 parse_date 构造真实的日期对象。这是控制台的输出：

boundaries_dates, Array [
    Mon Sep 23 2013 00:00:00 GMT+0200 , 
    Sun Sep 22 2013 00:00:00 GMT+0200 ]
domain extent, Array [
    Sat Sep 07 2013 00:00:00 GMT+0200 , 
    Sun Sep 22 2013 00:00:00 GMT+0200 ]

如您所见，范围是错误的，而不是我今天的 2013-09-07。我想有最短的日期。

让我烦恼的是，如果我将范围发送到比例域，则 scale.domain() 会返回我想要的值。（所以有一种方法可以得到我想要的，但感觉不对）。

所以，

如何使用 d3.extent() 获得正确的范围？

如何从不包含它的数组中获取正确的第一个日期？

谢谢

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0 回答 0