nowherenearithaca

This is an example of creating what could be a legend for a heat map, demonstrating the simple use of a data-driven linear gradient with D3.

	d3_selectionPrototype.append = function(name) {
	name = d3.ns.qualify(name);

	function append() {
	return this.appendChild(document.createElementNS(this.namespaceURI, name));
	}

	function appendNS() {
	return this.appendChild(document.createElementNS(name.space, name.local));
	}

	qualify: function(name) {
	var i = name.indexOf(":"),
	prefix = name;
	if (i >= 0) {
	prefix = name.substring(0, i);
	name = name.substring(i + 1);
	}
	return d3_nsPrefix.hasOwnProperty(prefix)
	? {space: d3_nsPrefix[prefix], local: name}
	: name;

	var d3_nsPrefix = {
	svg: "http://www.w3.org/2000/svg",
	xhtml: "http://www.w3.org/1999/xhtml",
	xlink: "http://www.w3.org/1999/xlink",
	xml: "http://www.w3.org/XML/1998/namespace",
	xmlns: "http://www.w3.org/2000/xmlns/"
	};

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	<!DOCTYPE html>
	<html>
	<head>
	<meta name="viewport" content="initial-scale=1.0, user-scalable=no"/>
	<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true"></script>
	<script type="text/javascript" src="http://mbostock.github.com/d3/d3.js?1.29.1"></script>
	<style type="text/css">

	html, body, #map {
	width: 100%;