【发布时间】：2026-01-05 16:00:01
【问题描述】：
我有以下美国地图，显示了日食发生时日食带内或附近的每个县的当前预测天气状况。我希望能够显示指示全食区的北部、南部和中心线的线条，但我无法让它们正确缩放。
显示的红线应该是北线，但它没有按比例绘制。
这是代码，有什么想法吗？最底部的那一行
svg.append('path').datum(feature.geometry).attr('class', 'mine').attr("d", path2);
是我试图画线的地方。
谢谢
<!DOCTYPE html>
<meta charset="utf-8">
<style>
.counties {
fill: none;
stroke: #ddd;
}
.states {
fill: none;
stroke: #000;
stroke-linejoin: round;
}
.mine {
fill: #f00;
stroke: #f00;
stroke-linejoin: round;
}
</style>
<svg width="960" height="600"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/d3-scale-chromatic.v1.min.js"></script>
<script src="https://d3js.org/topojson.v2.min.js"></script>
<script>
var svg = d3.select("svg"),
width = +svg.attr("width"),
height = +svg.attr("height");
var unemployment = d3.map();
var path = d3.geoPath();
var path2 = d3.geoPath();
var x = d3.scaleLinear()
.domain([1, 10])
.rangeRound([600, 860]);
var color = d3.scaleThreshold()
.domain(d3.range(2, 10))
.range(d3.schemeBlues[9]);
var g = svg.append("g")
.attr("class", "key")
.attr("transform", "translate(0,40)");
g.selectAll("rect")
.data(color.range().map(function (d) {
d = color.invertExtent(d);
if (d[0] == null) d[0] = x.domain()[0];
if (d[1] == null) d[1] = x.domain()[1];
return d;
}))
.enter().append("rect")
.attr("height", 8)
.attr("x", function (d) {
return x(d[0]);
})
.attr("width", function (d) {
return x(d[1]) - x(d[0]);
})
.attr("fill", function (d) {
return color(d[0]);
});
g.append("text")
.attr("class", "caption")
.attr("x", x.range()[0])
.attr("y", -6)
.attr("fill", "#000")
.attr("text-anchor", "start")
.attr("font-weight", "bold")
.text("Forecast Conditions");
g.call(d3.axisBottom(x)
.tickSize(13)
.tickFormat(function (x, i) {
//return i ? x : x;
if (i == 0)
return "Clear";
else if (i == 7)
return "Rain";
else
return "";
})
.tickValues(color.domain()))
.select(".domain")
.remove();
d3.queue()
.defer(d3.json, "https://d3js.org/us-10m.v1.json")
.defer(d3.tsv, "unemployment.tsv", function (d) {
var forecast = {
forecastNum: d.forecastNum,
name: d.name,
forecastText: d.forecastText
};
unemployment.set(d.id, forecast);
})
.await(ready);
function ready(error, us) {
if (error) throw error;
var feature = {
type: "Feature",
properties: {},
geometry: {
type: "LineString",
coordinates: [
[136.9522, 45.1172],
[36.8017, 13.6517],
]
}
};
svg.append("g")
.attr("class", "counties")
.selectAll("path")
.data(topojson.feature(us, us.objects.counties).features)
.enter().append("path")
.attr("fill", function (d) {
return color(d.forecastNum = unemployment.get(d.id).forecastNum);
})
.attr("d", path)
.append("title")
.text(function (d) {
var fc = unemployment.get(d.id);
var s = fc.name + " " + fc.forecastText;
console.log('[' + s + "]");
return s;
});
svg.append("path")
.datum(topojson.mesh(us, us.objects.states, function (a, b) {
return a !== b;
}))
.attr("class", "states")
.attr("d", path)
;
// svg.append("circle").attr("r",50).attr("transform", function() {return "translate(" + projection([-75,43]) + ")";});
svg.append('path').datum(feature.geometry).attr('class', 'mine').attr("d", path2);
}
</script>
【问题讨论】：
标签： d3.js topojson map-projections