D3.js geoBottomley() Function

Last Updated : 18 Sep, 2020

D3.js is a JavaScript library for producing dynamic, interactive data visualizations in web browsers. It makes use of Scalable Vector Graphics, HTML5, and Cascading Style Sheets standards.

The geoBottomley() function in d3.js is used to draw the Bottomley projection which draws lines of latitude as concentric circular arcs, with arc lengths equal to their lengths on the globe, and placed symmetrically and equally spaced across the vertical central meridian.

Syntax:

d3.geoBottomley()

Parameters: This method does not accept any parameters.

Return Value: This method creates a Bottomley projection from given JSON data.

Example 1: The following example makes Bottomley projection of the world with the center at (0,0) and no rotation.

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:500px;"> 
        <center> 
            <h3 style="color:black"> 
            </h3> 
        </center> 
        <svg width="600" height="450"> 
        </svg> 
    </div> 
  
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Bottomley projection 
        // Center(0,0) with 0 rotation 
        var gfg = d3.geoBottomley() 
            .scale(width / 1.5 / Math.PI) 
            .rotate([0, 0]) 
            .center([0, 0]) 
            .translate([width / 2, height / 2]) 
  
        // Loading the json 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", "Black") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
            }) 
    </script> 
</body> 
  
</html> 

Output:

Example 2: The following example makes Bottomley projection of the world after customizing the center and rotation.

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:900px;"> 
        <center> 
            <h3 style="color:black"> 
            </h3> 
        </center> 
        <svg width="400" height="450"> 
        </svg> 
    </div> 
  
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Bottomley  projection 
        // Center(0,20) and 45 degree  
        // rotation w.r.t Y axis 
        var gfg = d3.geoBottomley() 
            .scale(width / 1.5 / Math.PI) 
            .rotate([-45, 0]) 
            .center([0, 20]) 
            .translate([width / 2, height / 2]) 
  
        // Loading the json 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", "DarkOliveGreen") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
            }) 
    </script> 
</body> 
  
</html> 