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 geoEquirectangular() function in d3.js is used to draw the equirectangular projection which is a simple map projection attributed to Marinus of Tyre, who Ptolemy claims invented the projection.
Syntax:
d3.geoEquirectangular()
Parameters: This method does not accept any parameters.
Return Value: This method creates an Equirectangular projection from given json data.
Example 1: The following example makes Equirectangular 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" />
</script>
</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");
// Equirectangular projection
// Center(0,0) and no rotation
var gfg = d3.geoEquirectangular()
.scale(width / 1.5 / 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) {
// 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:
Equirectangular projection with no rotation and centered at (0,0)
Example 2: The following example makes Equirectangular projection of world with changing the center and 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:900px;">
<svg width="400" height="450">
</svg>
</div>
<script>
var svg = d3.select("svg"),
width = +svg.attr("width"),
height = +svg.attr("height");
// Equirectangular projection
// Center(0,10) and 45 degree
// anticlock rotation
var gfg = d3.geoEquirectangular()
.scale(width / 1.5 / Math.PI)
.rotate([45, 0])
.center([0, 10])
.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", "grey")
.attr("d", d3.geoPath()
.projection(gfg)
)
.style("stroke", "#ffff")
})
</script>
</body>
</html>
|
Output:
Equirectangular projection with 45 degree anti-clock rotation and centered at (0,10)