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View gist:0cc51e3336e71906c58fd4c5bea87a27
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View gist:75611aea890afe21b234
c_cyan=`tput setaf 6`
c_red=`tput setaf 1`
c_green=`tput setaf 2`
c_sgr0=`tput sgr0`
parse_git_branch ()
{
if git rev-parse --git-dir >/dev/null 2>&1
then
gitver="[$(git branch 2>/dev/null| sed -n '/^\*/s/^\* //p')]"
View README.md

This demonstrates raster-based reverse geocoding using canvas and D3.js. Geocoding is based on the color of the pixel at a given projected position. Note that the canvas is only shown here for the sake of explanation and debugging - this would in fact probably work faster if the canvas was not attached to the document at all.

The biggest remaining issue here is precision, which depends on:

  • the size of the canvas, and
  • the projection used.

Determining the optimum size based on the accuracy of your data is left as an exercise for the reader. Edge cases will also fail here, generally returning null - one option might be to stroke neighborhoods in a color, and then return an "uncertain" value for any non-grayscale pixel.

View index.html
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<title>One Graph</title>
<script type="text/javascript" src="http://mbostock.github.com/d3/d3.v2.js"></script>
<script type="text/javascript" src="simple-graph.js"></script>
<style type="text/css">
body { font: 13px sans-serif; }
rect { fill: #fff; }
View index.html
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8">
<title>Histogram</title>
<script type="text/javascript" src="http://mbostock.github.com/d3/d3.v2.min.js"></script>
<style type="text/css">
body {
margin: 3em;
}
View fitProjection.js
function fitProjection(projection, data, box, center) {
// get the bounding box for the data - might be more efficient approaches
var left = Infinity,
bottom = -Infinity,
right = -Infinity,
top = Infinity;
// reset projection
projection
.scale(1)
.translate([0, 0]);
View index.html
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<title>Beeswarm plot - collision detection</title>
<script type="text/javascript" src="http://mbostock.github.com/d3/d3.js"></script>
<script type="text/javascript" src="http://mbostock.github.com/d3/d3.geom.js"></script>
<script type="text/javascript" src="http://mbostock.github.com/d3/d3.layout.js"></script>
</head>
<body>
View progsvc.php
<?
// get timestamps
$start = strtotime($_GET['start']);
$end = strtotime($_GET['end']);
$cb = $_GET['callback'];
// start data
echo "$cb([";