Handling class attribute assignments in Polymaps - css

Question

I'm a social science person increasingly getting into web programming for data vis work so apologies if this question is dumb. I'm working on a polymaps implementation to visualize country level data over time. I reads in json temporal data and a geojson world map and spits out a quantile chloropleth map that iterates over monthly entries. The heart of this is a country formating function that binds a colorbrewer class to the country geojson objects (see below). This works find for the animation portion. The problem is that I am using a custom d3 layer that displays the date of the data currently displayed and acts as a mouseover control to stop the animation and choose a date or to choose a date once the animation is through. It does this by creating an blank svg element that uses the d3.scale() function to round mouse input to an integer that matches the index of the month desired. I've front loaded all the other calculations on load so that the only thing that happens at mouse over is the change of svg class (this is basically the same as Tom Carden's wealth of nations implementation on Bostock's d3 page here). Unfortunately, this still overloads the browser pretty quickly. Is there another way to do this that I'm totally missing? I admit im new to geojson so maybe some way to construct an array of classes with in the class attribute of the geojson object? Thanks a ton of any help.
function foo(local, geojson){
for(var x=0;x<geojson.length;x++){
var n = geojson[x].data.properties.name;
n$(geojson[x].element)
.attr("class", geojson[x].data.formats[local])
.add("svg:title");
}
}
EDIT: I'm adding the full script below.
<meta charset="utf-8">
<script src="scripts/d3.v3.js"></script>
<script src="scripts/polymaps.js"></script>
<script src="scripts/nns.js"></script>
<script>
//Polymaps namespace
var po = org.polymaps;
//Chart dimensions
var margin = {top: 20, right: 20, bottom: 20, left: 20};
var w = 960 - margin.right;
var h = 500 - margin.top - margin.bottom;
// Create the map object, add it to #map div
var map = po.map()
.container(d3.select("#map").append("svg:svg").attr("width", w + margin.left + margin.right).attr("height",h +margin.top + margin.bottom).node())
.center({lat: 28, lon: 0})
.zoom(1.85)
.zoomRange([1.5, 4.5])
.add(po.interact());
// Add the CloudMade image tiles as a base layer…
map.add(po.image()
.url(po.url("http://{S}tile.cloudmade.com"
+ "/1a1b06b230af4efdbb989ea99e9841af" // http://cloudmade.com/register
+ "/20760/256/{Z}/{X}/{Y}.png")
.hosts(["a.", "b.", "c.", ""])));
//Import contribution data
d3.json("assets/contributionsTCC1990-1991.json", function(data){
//find length of json data object and loop over it at interval
var dataLength = Object.keys(data).length;
//Create date key/value array using construtor
function date_array_constructor() {
var dateArray = {};
for(var i = 0; i < dataLength; i++) {
var d = i + 1;
dateArray[d] = data[i].date;
}
return dateArray;
}
var dateArray = date_array_constructor();
// Insert date label/control layer and add SVG elements that take on attributes determined by load function
var labelLayer = d3.select("#map svg").insert("svg:g");
map.add(po.geoJson()
.url("assets/world.json")
.tile(false)
.zoom(3)
.on("load", load));
map.container().setAttribute("class", "Blues");
map.add(po.compass()
.pan("none"));
function find_max(data, dataLength) {
var max = 0;
for(var i in data) {
if(data[i] > max) {
max = data[i] + 1;
}
}
return max;
}
function max_array_constructor(data, dataLength) {
var maxArray = {};
for(var i=0;i<dataLength;i++) {
var d = i+1;
maxArray[d] = find_max(data[i].contributions);
}
return maxArray;
}
var maxArray = max_array_constructor(data, dataLength);
function contribution_array_constructor(data, dataLength, tccName, feature) {
var contributions = {};
//iterate over date entries
for(var i=0;i<dataLength;i++) {
//contribution iterator
contributions[i+1] = 0;
for(x in data[i].contributions){
if(x == tccName) {
contributions[i+1] = data[i].contributions[x];
}
}
}
return contributions;
}
function format_array_constructor(data, dataLength, maxArray, feature) {
var formats = {};
// console.log(feature.data.contributions);
//iterate over date entries
for(var i=0;i<dataLength;i++) {
var percentile = feature.data.contributions[i+1] / maxArray[i+1];
if(percentile != 0){
var v = "q" + ((~~(percentile*7)) + 2) + "-" + 9;
}else{
var v = "countries";
}
formats[i+1] = v;
}
return formats;
}
///////////////////////////////
//load function
///////////////////////////////
function load(e) {
//Bind geojson and json
var geojson = e.features;
console.log(geojson);
geojson.dates = dateArray;
for(var x = 0; x < geojson.length; x++) {
// var tccID = geojson[x].data.id;
var tccName = geojson[x].data.properties.name;
geojson[x].data.contributions = contribution_array_constructor(data, dataLength, tccName, geojson[x]);
geojson[x].data.formats = format_array_constructor(data, dataLength, maxArray, geojson[x]);
}
//Insert date label
var dateLabel = labelLayer.append("text")
.attr("class", "date label")
.attr("text-anchor", "end")
.attr("x", w-670)
.attr("y", h )
.text(dateArray[1]);
//Add interactive overlay for date label
var box = dateLabel.node().getBBox();
var overlay = labelLayer.append("rect")
.attr("class", "overlay")
.attr("x", box.x)
.attr("y", box.y)
.attr("opacity",0)
.attr("width", box.width)
.attr("height", box.height)
.on("mouseover",enable_interaction);
function country_class_constructor(local, geojson){
for(var x=0;x<geojson.length;x++){
var n = geojson[x].data.properties.name;
n$(geojson[x].element)
.attr("class", geojson[x].data.formats[local])
.add("svg:title");
}
}
function foo(local, geojson){
for(var x=0;x<geojson.length;x++){
var n = geojson[x].data.properties.name;
n$(geojson[x].element)
.attr("class", geojson[x].data.formats[local])
.add("svg:title");
}
}
//incrementor function
function incrementor(local, geojson, dateArray) {
setTimeout(function() {
//set date label to current iteration
d3.transition(dateLabel).text(dateArray[local]);
//construct country classes
country_class_constructor(local, geojson);
// console.log(geojson);
}, 500*local);
}
///////////////////////////////
//Increment on load
///////////////////////////////
country_class_constructor(1, geojson)
for(var i=1; i< dataLength; i++) {
//Set incrementer as local variable
var local = i+1;
var timer = incrementor(local, geojson, dateArray);
}
///////////////////////////////
//interaction element
///////////////////////////////
function enable_interaction(){
var dateScale = d3.scale.linear()
.domain([1,Object.keys(dateArray).length])
.range([box.x + 10, box.x + box.width - 10])
.clamp(true);
timer = null;
overlay
.on("mouseover", mouse_over)
.on("mouseout",mouse_out)
.on("mousemove",mouse_move)
.on("touchmove",mouse_move);
function mouse_over() {
dateLabel.classed("active", true);
}
function mouse_out() {
dateLabel.classed("active", false);
}
function mouse_move() {
update_map(dateScale.invert(d3.mouse(this)[0]),data);
// displayYear(dateScale.invert(d3.mouse(this)[0]));
}
function update_map(userInput) {
var date = Math.floor(userInput);
d3.transition(dateLabel).text(dateArray[date]);
// console.log(date);
// country_class_constructor(date, geojson);
foo(date, geojson);
}
}
}
});
</script>
Edit 2: I forgot to add the JSON format. See below for two months of data:
[
{"date":"11/90",
"contributions":{
"Algeria":7,
"Argentina":39,
"Australia":41,
"Austria":967,
"Bangladesh":5,
"Belgium":4,
"Brazil":27,
"Canada":1002,
"Chile":7,
"China":5,
"Colombia":12,
"Czech Republic":6,
"Denmark":374,
"Ecuador":21,
"Fiji":719,
"Finland":992,
"France":525,
"Germany":13,
"Ghana":892,
"Hungary":15,
"India":40,
"Indonesia":5,
"Ireland":814,
"Italy":79,
"Jordan":6,
"Kenya":7,
"Malaysia":15,
"Nepal":851,
"Netherlands":15,
"New Zealand":22,
"Nigeria":2,
"Norway":924,
"Poland":165,
"Republic of the Congo":6,
"Russia":35,
"Senegal":4,
"Serbia":17,
"Spain":63,
"Sweden":738,
"Switzerland":5,
"Turkey":2,
"United Kingdom":769,
"United States":33,
"Uruguay":10,
"Venezuela":23,
"Zambia":6
}
},
{"date":"12/90",
"contributions":{
"Algeria":7,
"Argentina":39,
"Australia":41,
"Austria":967,
"Bangladesh":5,
"Belgium":4,
"Brazil":27,
"Canada":1002,
"Chile":7,
"China":5,
"Colombia":12,
"Czech Republic":6,
"Denmark":374,
"Ecuador":21,
"Fiji":719,
"Finland":992,
"France":525,
"Germany":13,
"Ghana":892,
"Hungary":15,
"India":40,
"Indonesia":5,
"Ireland":814,
"Italy":79,
"Jordan":6,
"Kenya":7,
"Malaysia":15,
"Nepal":851,
"Netherlands":15,
"New Zealand":22,
"Nigeria":2,
"Norway":924,
"Poland":165,
"Republic of the Congo":6,
"Russia":35,
"Senegal":4,
"Serbia":17,
"Spain":63,
"Sweden":738,
"Switzerland":5,
"Turkey":2,
"United Kingdom":769,
"United States":33,
"Uruguay":10,
"Venezuela":23,
"Zambia":6
}
}
]

Answer 1

After hours of debugging, it turns out that the nns.js library was causing me problems. Each iteration of the animation was creating a new set of DOM objects which started to max out the browser at 25,000. The solution was to use nss to create the initial state and then using the following function to change the class of each svg element.
function country_class_constructor(local, geojson){
for(var x=0;x<geojson.length;x++){
var n = geojson[x].data.properties.name;
element = document.getElementById(n);
element.className["animVal"] = geojson[x].data.formats[local];
element.className["baseVal"] = geojson[x].data.formats[local];
}