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April 6 class
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license: mit |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
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<!DOCTYPE html> | |
<meta charset="utf-8"> | |
<style> | |
body { | |
margin: 0; | |
} | |
.info { | |
color: #000; | |
position: absolute; | |
top: 450px; | |
left: 800px; | |
} | |
path { | |
fill: none; | |
stroke: red; | |
stroke-linejoin: round; | |
stroke-width: 1.5px; | |
} | |
</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(960, window.innerWidth), | |
height = Math.max(500, window.innerHeight); | |
// Initialize the projection to fit the world in a 1×1 square centered at the origin. | |
var projection = d3.geoMercator() | |
.scale(1 / tau) | |
.translate([0, 0]); | |
var info = d3.select("body").append("div") | |
.attr("class", "info"); | |
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) | |
.on("mousemove", mousemoved); | |
var raster = svg.append("g"); | |
var vector = svg.append("path"); | |
var quakes = svg.append("g") | |
var us = "https://umbcvis.github.io/classes/class-03/us.json"; | |
var usgs = "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_week.geojson"; | |
d3.queue() | |
.defer(d3.json, us) | |
.defer(d3.json, usgs) | |
.await(ready); | |
function ready(error, us, usgs) { | |
if (error) throw error; | |
vector | |
.datum(topojson.mesh(us, us.objects.us)); | |
// Compute the projected initial center. | |
var center = projection([-98.5, 39.5]); | |
quakes = quakes.selectAll(".quake") | |
.data(usgs.features) | |
.enter().append('path') | |
.attr('class', 'quake') | |
.attr('d', path) | |
.style('fill', 'crimson') | |
// 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) | |
.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); | |
quakes.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 "http://" + "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 + ")"; | |
} | |
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> |
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