D3.js geoHomolosine() Function

Last Updated : 23 Sep, 2020

The JavaScript D3.js library gives dynamic and interactive data visualizations for web pages using HTML5, Scalable Vector Graphics, and Cascading Style Sheets.
The geoHomolosine() function in d3.js is used to draw the pseudocylindrical, equal-area Goode homolosine projection.

Syntax:

d3.geoHomolosine()

Parameters: This method does not accept any parameters.

Return Value: This method creates Homolosine projection from the given JSON data.

Example 1: The following example draws Homolosine projection of world with center at (0, 0) and 0 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:600px;"> 
        <svg width="700" height="400"></svg> 
    </div> 
  
    <script> 
  
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Homolosine  projection 
        // Center(0, 0) and no rotation  
        var gfg = d3.geoHomolosine() 
            .scale(width / 1.8 / 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", "Black") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
            }) 
    </script> 
</body> 
  
</html> 

Output: The following shows the Homolosine projection of World with no rotation and centered at (0, 0)

Example 2: The following example draws Homolosine projection of world after altering 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:600px;"> 
  
        <svg width="700" height="400"> 
        </svg> 
    </div> 
  
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Homolosine  projection 
        // Center(-10, -10) and 30 degree 
        // rotation w.r.t Y axis 
        var gfg = d3.geoHomolosine() 
            .scale(width / 1.8 / 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", "grey") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
            }) 
    </script> 
</body> 
  
</html> 