d3.js geo - rendering svg path - svg

Question

I'd like to create choropleth map of Czech Republic. Inspired by this article http://bl.ocks.org/mbostock/4060606, I have created this
http://jsfiddle.net/1duds8tz/2/
var width = 960;
var height = 500;
var svg = d3.select("body").append("svg").attr("width", width).attr("height", height);
var offset = [width / 2, height / 2];
var projection = d3.geo.mercator().scale(6000).center([15.474, 49.822]).translate(offset);
var path = d3.geo.path().projection(projection);
queue().defer(d3.json, "..map.geojson").await(ready);
function ready(error, reg) {
var group = svg.selectAll("g").data(reg.features).enter().append("g");
group.append("path").attr("d", path).attr("fill", "none").attr("stroke", "#222");
}
When I tried to fill svg path with some color, I ended on this
http://jsfiddle.net/1duds8tz/3/
group.append("path").attr("d", path).attr("fill", "red").attr("stroke", "#222");
There are odd values in path d attribute.
My GeoJSON data must be somehow faulty but I can't figure what is wrong.
Everything looks right here: https://gist.github.com/anonymous/4e51227dd83be8c2311d

Answer 1

Your geoJSON is corrupted and as a result your polygons are being drawn as the interiors of an infinitely bounded polygon. That's why when you attempt to give a fill to the path, it goes beyond the extent of the screen but still displays the border just fine. I tried to reverse the winding order of your coordinates array, and that seemed to fix all of them except for "Brno-venkov", which might be the source of your problems (especially given its administrative shape).
I'd suggest going back to where you created the original GeoJSON and try to re-export it with simplification. If you want to reverse the coordinates on your GeoJSON to correct the winding order, that's pretty simple:
geodata = d3.selectAll("path").data();
for (x in geodata) {geodata[x].geometry.coordinates[0] = geodata[x].geometry.coordinates[0].reverse()}
But this won't fix the problem polygon, nor will not reversing its coordinates.

Answer 2

In case you are familiar with svg manipulation you can try geojson2svg. This allows you manipulate svg in standard way but you have to code a little more. In case your application requires d3 for many other purpose then d3 is best solution.

Answer 3

I've got exactly the same problem with Mapzen's .geojson files.
.reverse()-ing isn't good enough, if you can't make sure all your data has the same winding order.
I solved it with this one:
https://www.npmjs.com/package/geojson-rewind
You'll need to have npm & require available
Install it, and save it to your project
npm i -g geojson-rewind
Import it, to make it useable
var rewind = require('geojson-rewind');
Use it on the data, in this case:
req = rewind(req);
Tip: If you are working with static data, you can do this only once on the console, and you're good to go.