D3 Examples - Class9

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<!DOCTYPE html>
<meta charset="utf-8">
<style>
​
body {
  margin: 4;
}
​
path {
  fill: none;
  stroke: black;
  stroke-linejoin: round;
  stroke-width: 0.5px;
}
​
path.quake {
  fill: crimson;
}
  
</style>
<svg>
​
</svg>
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="//d3js.org/d3-tile.v0.0.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>
​
var pi = Math.PI,
    tau = 2 * pi;
​
var width = Math.max(860, window.innerWidth),
    height = Math.max(600, window.innerHeight);
var data;  // declare a global variable
​
//Mousemove  
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
    .on("mousemove", mousemoved);
​
// Fit the world in a 1×1 square, centered on the origin.
var projection = d3.geoMercator()
    .scale(1 / tau)
    .translate([0, 0]);
​
var path = d3.geoPath()
    .projection(projection);
​
var tile = d3.tile()
    .size([width, height]);
​
var zoom = d3.zoom()
    .scaleExtent([1 << 11, 1 << 14])
    .on("zoom", zoomed);
​
var svg = d3.select("svg")
    .attr("width", width)
    .attr("height", height);
​
var raster = svg.append("g");
​
var vector = svg.append("path");
  
// Title
svg.append('text')
    .attr('x', width / 2)
    .attr('y', "5.3em")
    .style('font-size', '2.7em')
    .style('text-anchor', 'middle')
    .text('Earthquakes in the Last Week')
​
d3.json("https://gist.githubusercontent.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/us.json", function(error, us) {
  if (error) throw error;
​
  vector
      .datum(topojson.mesh(us, us.objects.states));
​
  // Compute the projected initial center.
  var center = projection([-98.5, 39.5]);
​
  // Apply a zoom transform equivalent to projection.{scale,translate,center}.
  svg
      .call(zoom)
      .call(zoom.transform, d3.zoomIdentity
          .translate(width / 2, height / 2)
          .scale(1 << 12.8)
          .translate(-center[0], -center[1]));
});
​
function zoomed() {
  var transform = d3.event.transform;
​
  var tiles = tile
      .scale(transform.k)
      .translate([transform.x, transform.y])
      ();
​
  projection
      .scale(transform.k / tau)
      .translate([transform.x, transform.y]);
​
  vector
      .attr("d", path);
​
  var image = raster
      .attr("transform", stringify(tiles.scale, tiles.translate))
    .selectAll("image")
    .data(tiles, function(d) { return d; });
​
  image.exit().remove();
​
  image.enter().append("image")
      .attr("xlink:href", function(d) { return "https://" + "abc"[d[1] % 3] + ".tile.openstreetmap.org/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; })
      .attr("x", function(d) { return d[0] * 256; })
      .attr("y", function(d) { return d[1] * 256; })
      .attr("width", 256)
      .attr("height", 256);
}
​
function stringify(scale, translate) {
  var k = scale / 256, r = scale % 1 ? Number : Math.round;
  return "translate(" + r(translate[0] * scale) + "," + r(translate[1] * scale) + ") scale(" + k + ")";
}
var path = d3.geoPath()
    .projection(projection);
​
// Send earthquake data to function "plotQuakes"
var usgs = "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_week.geojson";
​
// Topojson for US states
var url = "https://umbcvis.github.io/classes/class-03/us.json"
​
d3.json(url, plotStates);
d3.json(usgs, plotQuakes);
​
function plotStates(error, json) {
​
// Convert topojson to an Array of GeoJSON features
// This defines "data", a global variable that can be manipulated in the developer console
  data = json.objects.us.geometries.map(function(d) { return topojson.feature(json, d); })
  
}
​
// Plot the earthquake data
function plotQuakes(error, json) {
  if (error) return console.log(error);
​
// Global variable: data, will be visible in Console
  data = json;
​
// Extract an array of feature objects, one for each earthquake
  var features = json.features;
​
// Plot the earthquakes
  var layer2 = svg.append("g");
​
  layer2.selectAll("path.quake")
      .data(features)
    .enter().append("path")
      .attr("class", "quake")
      .attr("d", path)
}
​
function mousemoved() {
  info.text(formatLocation(projection.invert(d3.mouse(this)), projection.scale()));
}
​
function formatLocation(p, k) {
  var format = d3.format("." + Math.floor(Math.log(k) / 2 - 2) + "f");
  return (p[1] < 0 ? format(-p[1]) + "°S" : format(p[1]) + "°N") + " "
       + (p[0] < 0 ? format(-p[0]) + "°W" : format(p[0]) + "°E");
}
  
</script>
    