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D3.js geoWagner4() Function
  • Last Updated : 23 Sep, 2020

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 geoWagner4() function in d3.js is used to draw The Wagner IV projection which is also known as Putniṇš P2´.

Syntax: 

d3.geoWagner4()

Parameters: This method does not accept any parameters.

Returns: This method creates and returns Wagner4 projection from given JSON data.



Example 1: The following example draws the Wagner4 projection of the world with the center at (0,0) and 0 rotation.

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<!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=
    </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");
  
        // Wagner4 projection
        // Center(0,0) with 0 rotation
        var gfg = d3.geoWagner4()
            .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){
                // 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>

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Output:

Wagner4 projection of World with no rotation and centered at (0,0)

Example 2: The following example draws the Wagner4 projection of the world after altering the center and rotation.

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<!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=
    </script>
</head
  
<body
    <div style="width:700px; height:600px;"
        <svg width="500" height="450"
        </svg
    </div
      
    <script>
        var svg = d3.select("svg"),
            width = +svg.attr("width"),
            height = +svg.attr("height");
  
        // Wagner4  projection
        // Center(-10,0) and 90 degree
        // rotation w.r.t Y axis
        var gfg = d3.geoWagner4()
            .scale(width / 1.3 / Math.PI)
            .rotate([-90,0])
            .center([-10,0])
            .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", "grey")
                    .attr("d", d3.geoPath()
                        .projection(gfg)
                    )
                    .style("stroke", "#ffff")
        })
    </script>
</body
  
</html>

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Output:

Wagner4 projection with 90-degree rotation w.r.t Y-axis and centered at (-10,0)

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