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@sierra073
Created November 5, 2018 23:44
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choropleth map
license: mit
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>D3: Setting path fills dynamically to generate a choropleth</title>
<script type="text/javascript" src="http://d3js.org/d3.v4.min.js"></script>
<style type="text/css">
/* No style rules here yet */
</style>
</head>
<body>
<script type="text/javascript">
//Width and height
var w = 500;
var h = 300;
//Define map projection
var projection = d3.geoAlbersUsa()
.translate([w/2, h/2])
.scale([500]);
//Define path generator
var path = d3.geoPath()
.projection(projection);
//Define quantize scale to sort data values into buckets of color
var color = d3.scaleQuantize()
.range(["rgb(237,248,233)","rgb(186,228,179)","rgb(116,196,118)","rgb(49,163,84)","rgb(0,109,44)"]);
//Colors derived from ColorBrewer, by Cynthia Brewer, and included in
//https://github.com/d3/d3-scale-chromatic
//Create SVG element
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
//Load in agriculture data
d3.csv("us-ag-productivity.csv", function(data) {
//Set input domain for color scale
color.domain([
d3.min(data, function(d) { return d.value; }),
d3.max(data, function(d) { return d.value; })
]);
//Load in GeoJSON data
d3.json("us-states.json", function(json) {
//Merge the ag. data and GeoJSON
//Loop through once for each ag. data value
for (var i = 0; i < data.length; i++) {
//Grab state name
var dataState = data[i].state;
//Grab data value, and convert from string to float
var dataValue = parseFloat(data[i].value);
//Find the corresponding state inside the GeoJSON
for (var j = 0; j < json.features.length; j++) {
var jsonState = json.features[j].properties.name;
if (dataState == jsonState) {
//Copy the data value into the JSON
json.features[j].properties.value = dataValue;
//Stop looking through the JSON
break;
}
}
}
//Bind data and create one path per GeoJSON feature
svg.selectAll("path")
.data(json.features)
.enter()
.append("path")
.attr("d", path)
.style("fill", function(d) {
//Get data value
var value = d.properties.value;
if (value) {
//If value exists…
return color(value);
} else {
//If value is undefined…
return "#ccc";
}
});
});
});
</script>
</body>
</html>
state value
Alabama 1.1791
Arkansas 1.3705
Arizona 1.3847
California 1.7979
Colorado 1.0325
Connecticut 1.3209
Delaware 1.4345
Florida 1.6304
Georgia 1.3891
Iowa 1.5297
Idaho 1.4285
Illinois 1.5297
Indiana 1.4220
Kansas 1.0124
Kentucky 0.9403
Louisiana 0.9904
Maine 1.3877
Maryland 1.2457
Massachusetts 1.1458
Michigan 1.1058
Minnesota 1.2359
Missouri 1.0212
Mississippi 1.1306
Montana 0.8145
North Carolina 1.3554
North Dakota 1.0278
Nebraska 1.1619
New Hampshire 1.0204
New Jersey 1.2831
New Mexico 0.8925
Nevada 0.9640
New York 1.1327
Ohio 1.2075
Oklahoma 0.7693
Oregon 1.3154
Pennsylvania 1.0601
Rhode Island 1.4192
South Carolina 1.1247
South Dakota 1.0760
Tennessee 0.7648
Texas 0.8873
Utah 0.9638
Virginia 0.9660
Vermont 1.0762
Washington 1.1457
Wisconsin 1.1130
West Virginia 0.5777
Wyoming 0.5712
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