d3.js geoHyperelliptical()用法及代码示例

JavaScript库D3.js使用HTML5，可缩放矢量图形和级联样式表为网页提供动态的交互式数据可视化。 d3.js库中的geoHyperelliptical()函数用于绘制伪圆柱equal-area Goode同型牛磺酸投影。

用法:

d3.geoHyperelliptical( k, alpha ,gamma)

参数：该方法接受上述和以下所述的三个参数。

k:定义子午线形状的超椭圆(或Lamé曲线)的 index 。默认值为2.5。
alpha:它控制圆柱投影的重量，该重量与超椭圆平均。默认值为0。
gamma:长宽比。默认值为1.183136。

返回值：此方法根据给定的JSON数据创建超椭圆投影。

范例1：下面的示例绘制以(0,0)为中心且旋转为0的世界的超椭圆投影。

HTML

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8" /> 
    <meta name="viewport" content= 
        "width=device-width, initial-scale=1.0" /> 
    <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;"> 
        <svg width="700" height="400"> 
        </svg> 
    </div> 
  
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Hyperelliptical projection 
        // Center(0,0) and no rotation  
        var gfg = d3.geoHyperelliptical() 
            .scale(width / 2.0 / Math.PI) 
            .rotate([0, 0]) 
            .center([0, 0]) 
            .translate([width / 2, height / 2]) 
  
        // Loading the json data 
        // Used json file stored at  
        // https://raw.githubusercontent.com/janasayantan 
        // datageojson/master/world.json 
        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", "seagreen") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
            }) 
    </script> 
</body> 
  
</html>

输出：

范例2：下面的示例在更改中心和旋转后绘制世界的超椭圆投影。

HTML

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8" /> 
    <meta name="viewport" content= 
    "width=device-width, initial-scale=1.0" /> 
    <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;"> 
        <svg width="700" height="400"></svg> 
    </div> 
  
    <script> 
  
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Hyperelliptical projection 
        // Center(-10,-10) and 30 degree  
        // rotation with respect to Y axis 
        var gfg = d3.geoHyperelliptical( 
            k = 3.0, alpha = 2, gamma = 2) 
            .scale(width / 2.0 / Math.PI) 
            .rotate([30, 0]) 
            .center([-10, -10]) 
            .translate([width / 2, height / 2]) 
  
        // Loading the json data 
        // Used json file stored at  
        // https://raw.githubusercontent.com 
        // /janasayantan/datageojson/master/world.json 
  
        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", "seagreen") 
                    .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 geoHyperelliptical() 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。