Tutorial 2 -- 'Hello world' using an XML stylesheet

Overview

Make sure you have mapnik (and the python bindings) installed and you've successfully run through Getting Started Python Tutorial.

This page will guide you through using the Mapnik python bindings along with a separate XML file for your map styles.
This tutorial expects that you are running Mapnik 2.x or greater. The command mapnik-config -v will show you which version you are running.

This tutorial covers using an XML stylesheet to rendering output that exactly matches the map output from the pure python example in Getting Started Python Tutorial.

Step 1: rendering script

First you will need a python script that sets the basic map parameters and points to the XML stylesheet. Copy the code below and save to a file called world_map.py.

#!/usr/bin/env python
import mapnik
stylesheet = 'world_style.xml'
image = 'world_style.png'
m = mapnik.Map(600, 300)
mapnik.load_map(m, stylesheet)
m.zoom_all() 
mapnik.render_to_file(m, image)
print "rendered image to '%s'" % image

Step 2: data

Now, we need some data to render. Let's use a shapefile of world border polygons from http://naturalearthdata.com. Download the data from this wiki's local cache here or directly from the Natural Earth Data site. Unzip the archive in the same directory as the world_map.py. Once unzipped, you should see four files like:

ne_110m_admin_0_countries.shp
ne_110m_admin_0_countries.shx
ne_110m_admin_0_countries.dbf
ne_110m_admin_0_countries.prj

To download and unzip on the command line with the do:

wget https://github.com/mapnik/mapnik/wiki/data/110m-admin-0-countries.zip
unzip 110m-admin-0-countries.zip # creates ne_110m_admin_0_countries.shp

Step 3: style

Finally, create the world_style.xml file referenced in the world_map.py script. Copy this XML and save to a file called world_style.xml, also in the same directory as world_map.py script.

<Map background-color="steelblue" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">

  <Style name="My Style">
    <Rule>
      <PolygonSymbolizer fill="#f2eff9" />
      <LineSymbolizer stroke="rgb(50%,50%,50%)" stroke-width="0.1" />
    </Rule>
  </Style>

  <Layer name="world" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
    <StyleName>My Style</StyleName>
    <Datasource>
      <Parameter name="type">shape</Parameter>
      <Parameter name="file">ne_110m_admin_0_countries.shp</Parameter>
    </Datasource>
  </Layer>

</Map>

Step 4: test

Now run the python script:

python world_map.py

It should output a png graphic in the same folder that matches the Getting Started Tutorial.

Hint: if you would like to run the script without first typing python you can do:

chmod +x world_map.py # to make it executable
./world_map.py