D3.js geoNellHammer() Function

Last Updated : 02 Oct, 2020

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

Syntax:

d3.geoNellHammer()

Parameters: This method does not accept any parameters.

Returns: This method creates the Nell–Hammer projection from given JSON data.

Example #1: The following example creates Nell–Hammer projection of world with center at (0, 0) and no rotation.

<!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"); 
  
             // Nell–Hammer projection 
             // Center(0,0) with 0 rotation 
             var gfg = d3.geoNellHammer() 
             .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){ 
  
            // Drawing the map 
            svg.append("g") 
               .selectAll("path") 
               .data(data.features) 
               .enter().append("path") 
                   .attr("fill", "DarkSlateBlue") 
                   .attr("d", d3.geoPath() 
                   .projection(gfg) 
                   ) 
                   .style("stroke", "#ffff") 
            }) 
        </script> 
    </body> 
</html> 

Output:

Example 2: In following example we will create Nell–Hammer projection of world with center at (0, 20) and rotating -45 degree with respect to Y axis.

<!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: 600px;"> 
            <center> 
                <h3 style="color: black;"></h3> 
            </center> 
  
            <svg width="500" 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"); 
  
            // NellHammer  projection 
     // Center(0,20) and -45 degree rotation w.r.t Y axis 
            var gfg = d3 
                .geoNellHammer() 
                .scale(width / 1.7 / Math.PI) 
                .rotate([-45, 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", "DarkTurquoise").attr( 
                  "d", d3.geoPath().projection(gfg)).style( 
                  "stroke", "#ffff"); 
            }); 
        </script> 
    </body> 
</html> 