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D3.js geoPolyconic() Function

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

Syntax:

d3.geoPolyconic()

Parameters: This method does not accept any parameters.

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

Example 1: The following example creates Polyconic 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=
    </script>
    <script>
        var svg = d3.select("svg"),
            width = +svg.attr("width"),
            height = +svg.attr("height");
  
        // Polyconic projection
        // Center(0, 0) with 0 rotation
        var gfg = d3
            .geoPolyconic()
            .scale(width / 2.0 / Math.PI)
            .rotate([0, 0])
            .center([0, 0])
            .translate([width / 2, height / 2]);
  
        // Loading the json data
        // Used json file stored at 
                    /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", "SeaGreen")
                    .attr("d", d3.geoPath().projection(gfg))
                    .style("stroke", "#ffff");
            });
    </script>
</body>
  
</html>


Output:

Example 2: In following example we will create Polyconic projection of world with center at (0, -20) and rotating 90 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=
    </script>
    <script>
        var svg = d3.select("svg"),
            width = +svg.attr("width"),
            height = +svg.attr("height");
  
        // Polyconic  projection
        // Center(0, -20) and 90 degree
        // rotation w.r.t Y axis
        var gfg = d3
            .geoPolyconic()
            .scale(width / 2.0 / Math.PI)
            .rotate([90, 0])
            .center([0, -20])
            .translate([width / 2, height / 2]);
  
        // Loading the json data
        // Used json file stored at 
                    /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", "SlateBlue")
                    .attr("d", d3.geoPath().projection(gfg))
                    .style("stroke", "#ffff");
            });
    </script>
</body>
  
</html>


Output:



Last Updated : 14 Oct, 2020
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