问题描述
我在玩D3的地理模块。我有D3的经验，但这是我第一次尝试地理模块。我采取了以下代码（从），最初显示美国地图（）在albers投影和修改为采取印度的Geojson（下面indiastates1.json）。该代码适用于美国文件，但不显示任何与印度json文件。
我在这里缺少一些东西。任何帮助是赞赏。我确实改变了投影到mercator。
I am playing around geo modules of D3.I have some experience with D3 but this is the first time I am trying out the geo modules. I have taken the following code (from https://github.com/alignedleft/d3-book/blob/master/chapter_12/04_fill.html) that originally displays US map(https://github.com/alignedleft/d3-book/edit/master/chapter_12/us-states.json) in albers projection and modified to take a Geojson of India(indiastates1.json below). The code works well with the US file, but does not display anything with India json file.Am I missing something here. Any help is appreciated. I did change the projection to mercator though.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>D3: Setting path fills</title>
<script type="text/javascript" src="../d3/d3.v3.js"></script>
<style type="text/css">
/* No style rules here yet */
</style>
</head>
<body>
<script type="text/javascript">
//Width and height
var w = 500;
var h = 300;
//Define map projection
var projection = d3.geo.mercator()
.translate([w/2, h/2])
.scale([500]);
//Define path generator
var path = d3.geo.path()
.projection(projection);
//Create SVG element
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
//Load in GeoJSON data
d3.json("indiastates1.json", function(json) {
//Bind data and create one path per GeoJSON feature
svg.selectAll("path")
.data(json.features)
.enter()
.append("path")
.attr("d", path)
.style("fill", "steelblue");
});
</script>
</body>
</html>
indiastates1.json
indiastates1.json
{"type":"FeatureCollection","features":[
{"type":"Feature","id":"IND","properties":{"name":"India"},"geometry":{"type":"Polygon","coordinates":[[[77.837451,35.49401],[78.912269,34.321936],[78.811086,33.506198],[79.208892,32.994395],[79.176129,32.48378],[78.458446,32.618164],[78.738894,31.515906],[79.721367,30.882715],[81.111256,30.183481],[80.476721,29.729865],[80.088425,28.79447],[81.057203,28.416095],[81.999987,27.925479],[83.304249,27.364506],[84.675018,27.234901],[85.251779,26.726198],[86.024393,26.630985],[87.227472,26.397898],[88.060238,26.414615],[88.174804,26.810405],[88.043133,27.445819],[88.120441,27.876542],[88.730326,28.086865],[88.814248,27.299316],[88.835643,27.098966],[89.744528,26.719403],[90.373275,26.875724],[91.217513,26.808648],[92.033484,26.83831],[92.103712,27.452614],[91.696657,27.771742],[92.503119,27.896876],[93.413348,28.640629],[94.56599,29.277438],[95.404802,29.031717],[96.117679,29.452802],[96.586591,28.83098],[96.248833,28.411031],[97.327114,28.261583],[97.402561,27.882536],[97.051989,27.699059],[97.133999,27.083774],[96.419366,27.264589],[95.124768,26.573572],[95.155153,26.001307],[94.603249,25.162495],[94.552658,24.675238],[94.106742,23.850741],[93.325188,24.078556],[93.286327,23.043658],[93.060294,22.703111],[93.166128,22.27846],[92.672721,22.041239],[92.146035,23.627499],[91.869928,23.624346],[91.706475,22.985264],[91.158963,23.503527],[91.46773,24.072639],[91.915093,24.130414],[92.376202,24.976693],[91.799596,25.147432],[90.872211,25.132601],[89.920693,25.26975],[89.832481,25.965082],[89.355094,26.014407],[88.563049,26.446526],[88.209789,25.768066],[88.931554,25.238692],[88.306373,24.866079],[88.084422,24.501657],[88.69994,24.233715],[88.52977,23.631142],[88.876312,22.879146],[89.031961,22.055708],[88.888766,21.690588],[88.208497,21.703172],[86.975704,21.495562],[87.033169,20.743308],[86.499351,20.151638],[85.060266,19.478579],[83.941006,18.30201],[83.189217,17.671221],[82.192792,17.016636],[82.191242,16.556664],[81.692719,16.310219],[80.791999,15.951972],[80.324896,15.899185],[80.025069,15.136415],[80.233274,13.835771],[80.286294,13.006261],[79.862547,12.056215],[79.857999,10.357275],[79.340512,10.308854],[78.885345,9.546136],[79.18972,9.216544],[78.277941,8.933047],[77.941165,8.252959],[77.539898,7.965535],[76.592979,8.899276],[76.130061,10.29963],[75.746467,11.308251],[75.396101,11.781245],[74.864816,12.741936],[74.616717,13.992583],[74.443859,14.617222],[73.534199,15.990652],[73.119909,17.92857],[72.820909,19.208234],[72.824475,20.419503],[72.630533,21.356009],[71.175273,20.757441],[70.470459,20.877331],[69.16413,22.089298],[69.644928,22.450775],[69.349597,22.84318],[68.176645,23.691965],[68.842599,24.359134],[71.04324,24.356524],[70.844699,25.215102],[70.282873,25.722229],[70.168927,26.491872],[69.514393,26.940966],[70.616496,27.989196],[71.777666,27.91318],[72.823752,28.961592],[73.450638,29.976413],[74.42138,30.979815],[74.405929,31.692639],[75.258642,32.271105],[74.451559,32.7649],[74.104294,33.441473],[73.749948,34.317699],[74.240203,34.748887],[75.757061,34.504923],[76.871722,34.653544],[77.837451,35.49401]]]}}
]}
推荐答案
错误的地方。我认为d3自动集中在美国与这些地理投射。所有你需要做的是使用transform将'India'移动到svg视口。具体来说，您需要将视口的原点转换为坐标以x，y像素指定的位置，或者至少是我的想法。要查看印度，我试过
You're (or the browser) just looking in the wrong place. I think that d3 automatically centres on the US with these geo projections. All you need to do is to use transform to move 'India' on to the svg viewport. Specifically, you need to translate the origin of the viewport to a location specified by coordinates in x,y pixels - or at least that's the way I think of it. To see India I tried
.attr("transform", "translate(-800,200)")
它似乎做这项工作。
如果你检查元素，选择这些东西很容易，你可以使用路径给你一些提示转化的地方。
It's pretty easy to pick these things up if you inspect the element, you can then use the path to give you some hints where to transform.
UPDATE
一个更好的方法是这个问题是计算中心和比例，在此中概述。特别是Jan和Mike的答案都很好。此外，还会解释此中的代码 - 第二个帖子。
A far better approach is to this problem would be to compute the center and scale such as outlined in this question and answer. In particular the answer by Jan and Mike are both excellent. There is also an explaination of the code in this google groups discussion - the second last post.
这篇关于使用d3.js和geojson显示地图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！