D3.js geoPatterson() Function

Last Updated : 30 Sep, 2020

The JavaScript D3.js library provides interactive data visualizations for web page using HTML5, Scalable Vector Graphics, and Cascading Style Sheets. The geoPatterson() function in d3.js is used to draw the Patterson cylindrical projection.

Syntax :

d3.geoPatterson()

Parameters: This method does not accept any parameters.

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

Example 1: The following example creates Patterson projection of world with 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"/>  
</head>  
<body>  
    <div style="width:700px; height:500px;">  
        <center>   
            <h3 style="color:black"></h3>   
        </center> 
          
        <svg width="600" height="450">  
        </svg>  
    </div>  
    <script src="https://d3js.org/d3.v4.js"></script> 
    <script src= 
"https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
  
    <script> 
  
        var svg = d3.select("svg"), 
        width = +svg.attr("width"), 
        height = +svg.attr("height"); 
  
        // Patterson projection 
        // Center(0,0) with 0 rotation 
        var gfg = d3.geoPatterson() 
                   .scale(width / 2.4 / 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){ 
  
           // Drawing 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: In the following example, we will create Patterson projection of world with center at (0, -20) and rotating 90 degree with respect to Y axis.

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;">  
        <center>  
            <h3 style="color:black"></h3>   
        </center> 
        <svg width="500" height="450">  
        </svg>  
    </div>  
  
    <script> 
  
        var svg = d3.select("svg"), 
        width = +svg.attr("width"), 
        height = +svg.attr("height"); 
  
        // Patterson  projection 
        // Center(0,-20) and 90 degree 
        // rotation w.r.t Y axis 
        var gfg = d3.geoPatterson() 
                 .scale(width / 1.7 / Math.PI) 
                 .rotate([90,0]) 
                 .center([0,-20]) 
                 .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> 