D3.js geoGuyou() Function

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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 geoGuyou() function in d3.js is used to draw the Guyou hemisphere-in-a-square projection.

Syntax:

d3.geoGuyou()

Parameters: This method does not accept any parameters.

Return Value: This method creates and returns the Guyou hemisphere-in-a-square projection from given JSON data.

Example 1: The following example makes the Guyou 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;">  
        <svg width="600" height="450">  
        </svg>  
    </div>  
      
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Guyou projection 
        // Center(0,0) with 0 rotation 
        var gfg = d3.geoGuyou() 
            .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", "SeaGreen") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
        }) 
    </script> 
</body>  
  
</html>

Output :

Guyou projection of World with no rotation and centered at (0,0)

Example 2: The following example makes Guyou 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:500px; height:600px;">  
        <svg width="500" height="450">  
        </svg>  
    </div>  
      
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Guyou  projection 
        // Center(10,40) and 10 degree rotation w.r.t Y axis 
        var gfg = d3.geoGuyou() 
            .scale(width / 1.3 / Math.PI) 
            .rotate([0,10]) 
            .center([10,40]) 
            .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:

Guyou projection with 10-degree rotation w.r.t Y-axis and centered at (10,40)

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