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Created World population tutorial (markdown)

springmeyer 2012-01-09 09:56:18 -08:00
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World-population-tutorial.md Normal file

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## Step 2
### World Population XML
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>
```