我正在尝试使用 javascript D3 创建按县划分的弗吉尼亚州地图。我有geojson文件，在这里（目前它只有大约一半的县）：
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[-80.2338,36.8743],[-80.3433,36.8305],[-80.3926,36.7428],[-80.4474,36.7428],[-80.4638,36.7100],[-80.6336,36.9291],[-80.5460,36.9838],[-80.5186,37.0112],[-80.4912,36.9838],
[-80.4529,37.0222],[-80.3488,37.0222],[-80.1790,37.1153]]]]}},
{"type":"Feature","properties":{"kind":"county","name":"Fluvanna","state":"VA"},"geometry":{"type":"MultiPolygon","coordinates":[[[[-78.3059,38.0080],[-78.0649,37.9040],
[-78.1580,37.7506],[-78.1635,37.7506],[-78.2402,37.6904],[-78.4264,37.7396],[-78.4921,37.7944]]]]}},
{"type":"Feature","properties":{"kind":"county","name":"Franklin","state":"VA"},"geometry":{"type":"MultiPolygon","coordinates":[[[[-79.7847,37.2303],[-79.7792,37.2029],
[-79.6642,37.1427],[-79.5930,37.0441],[-79.6423,36.8579],[-79.6478,36.8524],[-79.7628,36.7867],[-79.9983,36.8305],[-80.0147,36.7812],[-80.0421,36.7921],[-80.0750,36.8469],
[-80.2338,36.8743],[-80.1024,37.0276],[-80.1297,37.1208],[-80.0312,37.1755],[-79.9545,37.1372],[-79.8449,37.2248]]],[[[-76.9257,36.7100],[-76.9093,36.6497],[-76.9695,36.6826]]]]}},
{"type":"Feature","properties":{"kind":"county","name":"Frederick","state":"VA"},"geometry":{"type":"MultiPolygon","coordinates":[[[[-78.3497,39.4649],[-78.2292,39.3937],
[-78.0321,39.2622],[-78.0321,39.2622],[-78.1526,39.0377],[-78.3114,39.0103],[-78.3388,39.1034],[-78.3935,39.1034],[-78.4538,39.0267],[-78.5414,39.0541],[-78.5086,39.0870],
[-78.4045,39.1691],[-78.4374,39.1965],[-78.3388,39.3499],[-78.3662,39.3608]]],[[[-78.1635,39.1965],[-78.2019,39.1801],[-78.1854,39.1308],[-78.1361,39.1856]]]]}},
{"type":"Feature","properties":{"kind":"county","name":"Fredericksburg","state":"VA"},"geometry":{"type":"MultiPolygon","coordinates":[[[[-77.5282,38.3093],[-77.4734,38.3202],
[-77.4460,38.2819],[-77.4898,38.2709]]]]}}
]}
这是我用来创建地图的 javascript 文件：
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>D3 Tutorial</title>
<script src="http://d3js.org/d3.v3.min.js"> </script>
</head>
<body>
<script>
var canvas = d3.select("body").append("svg")
.attr("width", 760)
.attr("height", 760);
d3.json("virginia.geojson", function(data) {
var group = canvas.selectAll("g")
.data(data.features)
.enter()
.append("g");
var projection = d3.geo.mercator().scale(7300).translate([0,1980]);
var path = d3.geo.path().projection(projection);
var areas = group.append("path")
.attr("d", path)
.attr("class", "area")
.attr("fill", "steelblue");
});
</script>
</body>
</html>
这是我打开它时得到的：
我认为地图可能太大了，但即使我将画布的大小翻倍，整个东西还是一个蓝色矩形。我不知道如何缩小它。