CODEWITHSUNDEEP
javascriptjsoncsvd3.jsgeojson
Jgreensie
Jgreensie

Reputation: 13

D3 heat map - Colour scale only showing one colour

I'm trying to make a heat map using data and json geo data from the ABS. For some reason when i test this out it only assigns one colour to all segments instead of assigning lighter/darker colours for higher/lower numbers. I believe that my code is assigning a value to each map segment in the json but for some reason the colour scale isn't being applied to these values.

Here's my d3 code:

<!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="d3.js"></script>
        <style type="text/css">
            /* No style rules here yet */
        </style>
    </head>
    <body>
        <script type="text/javascript">

            //Width and height
            var w = 1000;
            var h = 600;

            var path = d3.geoPath()
                         .projection(d3.geoMercator()
                         .center([151,-33.5])
                         .scale(17000)
                         .translate([w/2,h/2]));

            //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("ManagerArea.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("australia_adm2.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.sa4_name11;

                            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>

The naming in my json geo data:

{"type":"FeatureCollection", "features": [ {"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":...

..."properties":{"cartodb_id":1,"sa4_name11":"Sydney - Baulkham Hills and Hawkesbury","right_dpop":38742,"right_opop":69540,"right_xcoord":150.8288053,"right_ycoord":-33.36860558}},

My csv data:

state,value
Capital Region,15558
Central Coast,15642
Central West,13074
Coffs Harbour - Grafton,6274
Far West and Orana,7968
Hunter Valley exc Newcastle,11717
Illawarra,13278
Mid North Coast,8758
Murray,8298
New England and North West,12884
Newcastle and Lake Macquarie,15980
Richmond - Tweed,12013
Riverina,11055
Southern Highlands and Shoalhaven,7191
Sydney - Baulkham Hills and Hawkesbury,19904
Sydney - Blacktown,14710
Sydney - City and Inner South,27758
Sydney - Eastern Suburbs,24778
Sydney - Inner South West,27081
Sydney - Inner West,24055
Sydney - North Sydney and Hornsby,39796
Sydney - Northern Beaches,24080
Sydney - Outer South West,12403
Sydney - Outer West and Blue Mountains,15767
Sydney - Parramatta,20323
Sydney - Ryde,13468
Sydney - South West,15090
Sydney - Sutherland,16901

Result

Upvotes: 0

Views: 1499

Answers (1)

tgiachetti
tgiachetti

Reputation: 364

I think that the problem lies in this section: 

color.domain([
                    d3.min(data, function(d) { return d.value; }),
                    d3.max(data, function(d) { return d.value; })
                ]);

d.value is being treated as a string instead of a number. It should be a number. You could make it a number by using parseFloat(d.value) as mentioned on this post or by inserting unary plus: +d.value as used in Mike Bostock's choropleth.

Upvotes: 3

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