javascript - 在 .json 中查找最大值和最小值

对于我尝试使用 d3.js 绘制的图形，我需要为轴设置比例。

图的数据存储在一个 Json 文件中，结构如下:

[{
    "id" : "AustraliaNewZealand" ,
    "year" : [1990,1992,1994,1993,1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009,2010],
    "value":[477790,485825,487296,488885,502585,511718,526594,538967,550556,563572,577171,579126,591635,599216,604267,608954,615853,623685,618961,614920]
},
{
    "id":"CentralEurope",
    "year":[1990,1992,1994,1993,1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009,2010],
    "value":[1548736,1334452,1313088,1283248,1314709,1360546,1343907,1285511,1237278,1251872,1244069,1233778,1284639,1297510,1317861,1359787,1396681,1361445,1278731,1343044]
},
{
    "id":"EasternEurope",
    "year":[1990,1992,1994,1993,1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009,2010],
    "value":[4418516,3530464,3287987,2925644,2775181,2672238,2540975,2495036,2513372,2515375,2540796,2544848,2598148,2637682,2622241,2709974,2714204,2740248,2565213,2680226]
},
{
    "id":"NorthAmerica",
    "year":[1990,1992,1994,1993,1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009,2010],
    "value":[6750754,6821412,6948829,7059001,7166869,7386971,7460485,7509719,7573562,7790060,7675762,7710685,7769154,7896824,7918461,7841686,7966277,7751508,7277713,7493948]
},
{
    "id":"WesternEurope",
    "year":[1990,1992,1994,1993,1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009,2010],
    "value":[4365949,4290345,4222425,4221029,4264725,4353056,4290057,4310736,4251628,4260565,4306230,4278128,4333237,4337031,4305560,4267515,4209481,4125479,3841580,3924831]
}]

我想做的是在嵌套的各种数组之间进行迭代以获取年份和最小值和最大值，但我不知道如何获取这些值。我设法使用以下方法获取单个数组的值:

var xScale = d3 .time.scale()
                .domain((d3.extent(dataset[0].year)))
                .range([margin*2, (width - margin)]);
var yScale = d3 .scale.linear()
                .domain([0, d3.max(dataset[0].value)])
                .range([(height - margin), margin]);

其中 _dataset_ 是回调函数的标识符，但我想要的是获取所有数组之间的最小值和最大值(例如最小值在数组 3 中，最大值在数组 1 中)。我想我应该使用 for 循环，但我不知道应该把它放在哪里以及如何设置它以查看所有数组。

最佳答案

如果我们在这里使用一点函数式编程而不是 for 循环，那就很有趣了:

d3.extent(dataset.reduce(function(a,b) { return a.concat(b.year) }, []))

你可以用这些值做同样的事情。

关于javascript - 在 .json 中查找最大值和最小值，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/19731820/