d3.js geoAzimuthalEquidistant()用法及代码示例

d3.js中的geoAzimuthalEquidistant()函数用于从给定的geojson数据绘制Azimuthal等距投影。这是一种Map投影，其中Map上的所有点均与中心点成比例地处于正确距离。同样，Map上的所有点都从中心点指向正确的方向。

用法:

d3.geoAzimuthalEquidistant()

参数：此方法不接受任何参数。

返回值：此方法返回方位角等距投影。

范例1：以下示例绘制了以(0,0)为中心的世界的方位角等距投影。

HTML

<html> 
  
<head> 
    <script src="https://d3js.org/d3.v4.js"> 
    </script> 
    <script src= 
"https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
</head> 
  
<body> 
    <div style="width:800px;  
              height:600px;"> 
        <center> 
            <h3 style="color:black"> 
                AzimuthalEquidistant Projection 
                of World 
            </h3> 
        </center> 
        <svg width="700" height="550"> 
        </svg> 
    </div> 
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // AzimuthalEquidistant projection 
        var gfg = d3.geoAzimuthalEquidistant() 
            .scale(width / 1.5 / Math.PI) 
            .translate([width / 2, height / 2]); 
  
        // Loading the geojson data 
        d3.json("https://raw.githubusercontent.com/" + 
            "janasayantan/datageojson/master/" + 
            "geoworld%20.json", 
            function (data) { 
  
                // Draw the map 
                svg.append("g") 
                    .selectAll("path") 
                    .data(data.features) 
                    .enter().append("path") 
                    .attr("fill", "Silver") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
            }); 
    </script> 
</body> 
  
</html>

输出：

范例2：以下示例使方位角等距投影以(-10,0)为中心，并相对于x轴旋转了10度anti-clockwise。

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src="https://d3js.org/d3.v4.js"> 
    </script> 
    <script src= 
"https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
</head> 
  
<body> 
    <div style="width:700px;  
              height:600px;"> 
        <center> 
            <h3 style="color:grey"> 
                AzimuthalEquidistant Projection 
                of World 
            </h3> 
        </center> 
        <svg width="700" height="550"> 
        </svg> 
    </div> 
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // AzimuthalEquidistant  projection 
        // Center(0,-10) and roating -10 degree 
        var gfg = d3.geoAzimuthalEquidistant() 
            .scale(width / 1.5 / Math.PI) 
            .rotate([-10, 0]) 
            .center([0, -10]) 
            .translate([width / 2, height / 2]); 
  
        // Loading the geojson data 
        d3.json("https://raw.githubusercontent.com/" + 
            "janasayantan/datageojson/master/" + 
            "world.json", 
            function (data) { 
  
                // Draw the map 
                svg.append("g") 
                    .selectAll("path") 
                    .data(data.features) 
                    .enter().append("path") 
                    .attr("fill", "green") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
            }); 
    </script> 
</body> 
  
</html>

输出：

相关用法

注：本文由纯净天空筛选整理自jana_sayantan大神的英文原创作品 D3.js geoAzimuthalEquidistant() Function。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。