I'm working with d3. I create a globe of countries from a json file. The globe has svg paths, and each path has an id. I want to select a path with a particular ID. How would I do that, please?
handleGlobe();
$('#panel div').click(function(){
if (this.className == 'represented') {
thisID = $(this).attr('id');
focusedCountry = d3.select('path') //??? not sure how to say this
p = d3.geo.centroid(focusedCountry);
}
...
handleGlobe() {
var feature;
var projection = d3.geo.azimuthal()
.scale(380)
.origin([-71.03,42.37])
.mode("orthographic")
.translate([380, 400]);
var circle = d3.geo.greatCircle()
.origin(projection.origin());
// TODO fix d3.geo.azimuthal to be consistent with scale
var scale = {
orthographic: 380,
stereographic: 380,
gnomonic: 380,
equidistant: 380 / Math.PI * 2,
equalarea: 380 / Math.SQRT2
};
var path = d3.geo.path()
.projection(projection);
var svg = d3.select("#globe").append("svg:svg")
.attr("width", 800)
.attr("height", 800)
.on("mousedown", mousedown);
d3.json("world-countries.json", function(collection) {
feature = svg.selectAll("path")
.data(collection.features)
.enter().append("svg:path")
.attr("d", clip)
.attr("id", function(d) { return d.id; })
.on("mouseover", pathOver)
.on("mouseout", pathOut)
.on("click", click);
feature.append("svg:title")
.text(function(d) { return d.properties.name; });
feature.each(function(){
for (var i=0; i<unrepresented.length; i++){
if ($(this).attr('id') == unrepresented[i]) {
d3.select(this).style("fill", "#ededed");
}
}
if (($(this).attr('id') == 'GRL') || ($(this).attr('id') == 'ATA')) { //Greenland and Antarctica are shapes, but not countries
d3.select(this).style("fill", "#ededed");
}
});
});
d3.select(window)
.on("mousemove", mousemove)
.on("mouseup", mouseup)
;
d3.select("select").on("change", function() {
projection.mode(this.value).scale(scale[this.value]);
refresh(750);
});
var m0,
o0;
function mousedown() {
m0 = [d3.event.pageX, d3.event.pageY];
o0 = projection.origin();
d3.event.preventDefault();
}
function mousemove() {
if (m0) {
var m1 = [d3.event.pageX, d3.event.pageY],
o1 = [o0[0] + (m0[0] - m1[0]) / 8, o0[1] + (m1[1] - m0[1]) / 8];
projection.origin(o1);
circle.origin(o1)
refresh();
}
}
function mouseup() {
if (m0) {
mousemove();
m0 = null;
}
}
function refresh(duration) {
(duration ? feature.transition().duration(duration) : feature).attr("d", clip);
}
function clip(d) {
return path(circle.clip(d));
}
function click() {
}
function pathOver() {
}
function pathOut() {
}
//end globe
}
SVG stands for Scalable Vector Graphics. SVG is an XML-based vector graphics format. It provides options to draw different shapes such as Lines, Rectangles, Circles, Ellipses, etc. Hence, designing visualizations with SVG gives you more power and flexibility.
d3. select selects the first matching element whilst d3. selectAll selects all matching elements. Both functions take a string as its only argument.
An SVG line element is represented by <line> tag. A line's attributes are: x1: This is the x-coordinate of the first point. y1: This is the y-coordinate of the first point.
svg. selectAll('rect') tells the browser to find the svg element and look inside it for any rectangles. If it finds rectangles, it returns them in a selection that is an array of elements.
You can select an element by ID by prefixing the ID with "#" and using that as a selector:
d3.select("#ID");
or to select a path with that ID
d3.select("path#ID");
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