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Updated Tutorial 2 -- 'Hello world' using an XML stylesheet (markdown)

springmeyer 2012-01-09 09:56:36 -08:00
parent 87f818d30d
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GettingStartedInXML.md

@ -8,11 +8,7 @@ Make sure you have mapnik (and the python bindings) installed and you've success
* 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.
Two examples are covered in this tutorial:
1) An XML stylesheet is rendering that exactly matches the map output from the pure python example in [Getting Started Python Tutorial](GettingStartedInPython).
2) An XML stylesheet is showcased that uses a world borders dataset with population attributes to create a chloropleth map (aka thematic) by population size.
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](GettingStartedInPython).
## Step 1
@ -32,14 +28,19 @@ mapnik.render_to_file(m, image)
print "rendered image to '%s'" % image
```
Now, we need some data to render, let's use a shapefile of world border polygons from http://www.naturalearthdata.com. You can download the data from this wiki's local copy [here](data/) or directly from the [Natural Earth Data site](http://www.naturalearthdata.com/http//www.naturalearthdata.com/download/110m/cultural/110m-admin-0-countries.zip). Unzip the archive and it should produce four files like `ne_110m_admin_0_countries.shp, ne_110m_admin_0_countries.shx, ne_110m_admin_0_countries.dbf, and ne_110m_admin_0_countries.prj`
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](data/110m-admin-0-countries.zip) or directly from the [Natural Earth Data site](http://www.naturalearthdata.com/http//www.naturalearthdata.com/download/110m/cultural/110m-admin-0-countries.zip). 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
Next, 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` in the same directory as `world_map.py` script.
Next, 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.
```xml
<Map background-color="steelblue" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
@ -68,167 +69,7 @@ Now run the python script:
* 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:
## Step 2
### World Population XML
Attached below and included as code samples, here is a sample python script that accesses a _'population.xml_ map configuration.
Note: you will need to download the [modified world borders shapefile](http://trac.mapnik.org/attachment/wiki/XMLGettingStarted/world_borders.zip).
* Note: this file is originally from [Thematic Mapping Blog](http://thematicmapping.org/downloads/world_borders.php). The version attached here is the simpler shapefile provided there with some modification made to avoid problems that occur when displaying the map in projections such as 900913/3785 (this tutorial does not use this projection so you can use the original shapefiles as well). See [ticket 308](https://github.com/mapnik/mapnik/issues/308) for details.
This script should result in a graphic like this:
[[/images/world_population_minimized.png]]
```python
#!/usr/bin/env python
import mapnik
mapfile = "population.xml"
m = mapnik.Map(1400, 600)
mapnik.load_map(m, mapfile)
bbox = mapnik.Envelope(mapnik.Coord(-180.0, -75.0), mapnik.Coord(180.0, 90.0))
m.zoom_to_box(bbox)
mapnik.render_to_file(m, 'world_population.png', 'png')
```
And here is the xml file:
```xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE Map>
<!-- Sample Mapnik XML template by Dane Springmeyer -->
<Map bgcolor="white" srs="+proj=latlong +datum=WGS84">
<Style name="population">
<Rule>
<!-- Built from Seven Class sequential YIGnBu from www.colorbrewer.org -->
<!-- Quantile breaks originally from QGIS layer classification -->
<Filter>[POP2005] = 0 </Filter>
<PolygonSymbolizer>
<CssParameter name="fill">#ffffcc</CssParameter>
</PolygonSymbolizer>
<!-- Outlines for Antarctica look good -->
<LineSymbolizer>
<CssParameter name="stroke">black</CssParameter>
<CssParameter name="stroke-width">.1</CssParameter>
</LineSymbolizer>
</Rule>
<Rule>
<Filter>[POP2005] &gt; 0 and [POP2005] &lt; 15000</Filter>
<PolygonSymbolizer>
<CssParameter name="fill">#c7e9b4</CssParameter>
</PolygonSymbolizer>
<!-- Outlines for Antarctica look good -->
<LineSymbolizer>
<CssParameter name="stroke">black</CssParameter>
<CssParameter name="stroke-width">.1</CssParameter>
</LineSymbolizer>
</Rule>
<Rule>
<Filter>[POP2005] &gt;= 15000 and [POP2005] &lt; 255000</Filter>
<PolygonSymbolizer>
<CssParameter name="fill">#7fcdbb</CssParameter>
</PolygonSymbolizer>
</Rule>
<Rule>
<Filter>[POP2005] &gt;= 255000 and [POP2005] &lt; 1300000</Filter>
<PolygonSymbolizer>
<CssParameter name="fill">#1d91c0</CssParameter>
</PolygonSymbolizer>
</Rule>
<Rule>
<Filter>[POP2005] &gt;= 1300000 and [POP2005] &lt; 4320000</Filter>
<PolygonSymbolizer>
<CssParameter name="fill">#41b6c3</CssParameter>
</PolygonSymbolizer>
</Rule>
<Rule>
<Filter>[POP2005] &gt;= 4320000 and [POP2005] &lt; 9450000</Filter>
<PolygonSymbolizer>
<CssParameter name="fill">#225ea8</CssParameter>
</PolygonSymbolizer>
</Rule>
<Rule>
<Filter>[POP2005] &gt;= 9450000 and [POP2005] &lt; 25650000</Filter>
<PolygonSymbolizer>
<CssParameter name="fill">#225ea8</CssParameter>
</PolygonSymbolizer>
</Rule>
<Rule>
<Filter>[POP2005] &gt;= 25650000 and [POP2005] &lt; 1134000000</Filter>
<PolygonSymbolizer>
<CssParameter name="fill">#122F7F</CssParameter>
</PolygonSymbolizer>
</Rule>
<Rule>
<ElseFilter/> <!-- This will catch all other values - in this case just India and China -->
<!-- A dark red polygon fill and black outline is used here to highlight these two countries -->
<PolygonSymbolizer>
<CssParameter name="fill">darkred</CssParameter>
</PolygonSymbolizer>
<LineSymbolizer>
<CssParameter name="stroke">black</CssParameter>
<CssParameter name="stroke-width">.7</CssParameter>
</LineSymbolizer>
</Rule>
</Style>
<Style name="countries_label">
<Rule>
<!-- Only label those countries with over 9 Million People -->
<!-- Note: Halo and Fill are reversed to try to make them subtle -->
<Filter>[POP2005] &gt;= 4320000 and [POP2005] &lt; 9450000</Filter>
<TextSymbolizer name="NAME" face_name="DejaVu Sans Bold" size="7" fill="black" halo_fill= "#DFDBE3" halo_radius="1" wrap_width="20" spacing="5" allow_overlap="false" avoid_edges="false" min_distance="10"/>
</Rule>
<Rule>
<!-- Only label those countries with over 9 Million People -->
<!-- Note: Halo and Fill are reversed to try to make them subtle -->
<Filter>[POP2005] &gt;= 9450000 and [POP2005] &lt; 25650000</Filter>
<TextSymbolizer name="NAME" face_name="DejaVu Sans Book" size="9" fill="black" halo_fill= "#DFDBE3" halo_radius="1" wrap_width="20" spacing="5" allow_overlap="false" avoid_edges="false" min_distance="10"/>
</Rule>
<Rule>
<!-- Those with over 25 Million get larger labels -->
<Filter>[POP2005] &gt;= 25650000 and [POP2005] &lt; 1134000000</Filter>
<TextSymbolizer name="NAME" face_name="DejaVu Sans Book" size="12" fill="white" halo_fill= "#2E2F39" halo_radius="1" wrap_width="20" spacing="5" allow_overlap="false" avoid_edges="true" min_distance="10"/>
</Rule>
<Rule>
<!-- Those with over 25 Million get larger labels -->
<!-- Note: allow_overlap is true here to allow India to sneak through -->
<Filter>[POP2005] &gt;= 1134000000</Filter>
<TextSymbolizer name="NAME" face_name="DejaVu Sans Book" size="15" fill="white" halo_fill= "black" halo_radius="1" wrap_width="20" spacing="5" allow_overlap="true" avoid_edges="true" min_distance="10"/>
</Rule>
</Style>
<Layer name="countries" srs="+proj=latlong +datum=WGS84" status="on">
<!-- Style order determines layering hierarchy -->
<!-- Labels go on top so they are listed second -->
<StyleName>population</StyleName>
<StyleName>countries_label</StyleName>
<Datasource>
<Parameter name="type">shape</Parameter>
<!-- FIXME -->
<!-- Note: 'TM_WORLD_BORDERS_SIMPL-0.3' is the name of the shapefile (without the .shp file extension) -->
<Parameter name="file">/PATH/TO/THE/TM_WORLD_BORDERS_SIMPL-0.3</Parameter>
</Datasource>
</Layer>
</Map>
```
chmod +x world_map.py # to make it executable
./world_map.py