Updated GettingStarted (markdown)
floledermann
parent
7ff10e487d
commit
64d4767411
1 changed files with 2 additions and 178 deletions
|
|
@ -1,181 +1,5 @@
|
|||
<!-- Name: GettingStarted -->
|
||||
<!-- Version: 26 -->
|
||||
<!-- Last-Modified: 2009/04/20 10:04:35 -->
|
||||
<!-- Author: phispi -->
|
||||
|
||||
Mapnik can be used in a variety of ways. The most widely used options are using XML config files, using the Python bindings or using the API directly in C++.
|
||||
|
||||
[Getting started using XML](XMLGettingStarted)
|
||||
|
||||
## Getting started in Python
|
||||
|
||||
### Step 1
|
||||
|
||||
Make sure you have mapnik installed. Depending on your installation path you may need to modify your `PYTHONPATH`, `/etc/ld.so.conf` or export `LD_LIBRARY_PATH`, or whatever your system requires.
|
||||
|
||||
The simple check is to start python interpreter from a command line by typing python
|
||||
and then just type:
|
||||
|
||||
|
||||
```python
|
||||
>>> import mapnik
|
||||
```
|
||||
|
||||
and if you don't see any complaints, you're on the right track. If you do, you have to check your installation again.
|
||||
|
||||
* Note: If you have built mapnik in debug mode you should see the available datasources listed, including:
|
||||
|
||||
```python
|
||||
>>> import mapnik
|
||||
registered datasource : gdal
|
||||
registered datasource : postgis
|
||||
registered datasource : raster
|
||||
registered datasource : shape
|
||||
```
|
||||
|
||||
### Step 2
|
||||
|
||||
The code below can be pasted into your python interpreter. Ideally paste line by line so you can confirm each step is working. The commented lines (#) should be able to be pasted without trouble, but depending on your interpreter setting may cause errors.
|
||||
|
||||
* See the code snippet in Step 3 for code without comments.
|
||||
|
||||
Import the mapnik python toolkit and setup the basic map parameters
|
||||
|
||||
```
|
||||
# import mapnik python bindings
|
||||
import mapnik
|
||||
# Instantiate a map object with given width, height and spatial reference system
|
||||
m = mapnik.Map(600,300,"+proj=latlong +datum=WGS84")
|
||||
# Set background colour to 'steelblue'.
|
||||
# You can use 'named' colours, #rrggbb, #rgb or rgb(r%,g%,b%) format
|
||||
m.background = mapnik.Color('steelblue')
|
||||
```
|
||||
|
||||
* Note, Mapnik accepts any projection that Proj.4 handles. See http://spatialreference.org for the proj4 strings for various projections. For example http://spatialreference.org/ref/epsg/4326/mapnikpython/ will give you the exact parameters for EPSG 4326.
|
||||
|
||||
|
||||
Create the Styles and Rules for the map symbology
|
||||
|
||||
```python
|
||||
# Now lets create a style and add it to the Map.
|
||||
s = mapnik.Style()
|
||||
# A Style can have one or more rules. A rule consists of a filter, min/max scale
|
||||
# demoninators and 1..N Symbolizers. If you don't specify filter and scale denominators
|
||||
# you get default values :
|
||||
# Filter = 'ALL' filter (meaning symbolizer(s) will be applied to all features)
|
||||
# MinScaleDenominator = 0
|
||||
# MaxScaleDenominator = INF
|
||||
# Lets keep things simple and use default value, but to create a map we
|
||||
# we still must provide at least one Symbolizer. Here we want to fill countries polygons with
|
||||
# greyish colour and draw outlines with a bit darker stroke.
|
||||
|
||||
r=mapnik.Rule()
|
||||
r.symbols.append(mapnik.PolygonSymbolizer(mapnik.Color('#f2eff9')))
|
||||
r.symbols.append(mapnik.LineSymbolizer(mapnik.Color('rgb(50%,50%,50%)'),0.1))
|
||||
s.rules.append(r)
|
||||
```
|
||||
|
||||
Connect the style information to your map and your data
|
||||
|
||||
```python
|
||||
# Here we have to add our style to the Map, giving it a name.
|
||||
m.append_style('My Style',s)
|
||||
|
||||
# Here we instantiate our data layer, first by giving it a name and srs (proj4 projections string), and then by giving it a datasource.
|
||||
lyr = mapnik.Layer('world',"+proj=latlong +datum=WGS84")
|
||||
# Then provide the full filesystem path to a shapefile in WGS84 or EPSG 4326 projection without the .shp extension
|
||||
# A sample shapefile can be downloaded from http://mapnik-utils.googlecode.com/svn/data/world_borders.zip
|
||||
lyr.datasource = mapnik.Shapefile(file='/Users/path/to/your/data/world_borders')
|
||||
lyr.styles.append('My Style')
|
||||
```
|
||||
|
||||
Finally add the layers to the map and zoom to the full extent of the data layer
|
||||
|
||||
```python
|
||||
m.layers.append(lyr)
|
||||
m.zoom_to_box(lyr.envelope())
|
||||
```
|
||||
|
||||
Finish up by making the world map image
|
||||
|
||||
```python
|
||||
# Write the data to a png image called world.png in the base directory of your user
|
||||
mapnik.render_to_file(m,'world.png', 'png')
|
||||
|
||||
# Exit the python interpreter
|
||||
exit() # or ctrl-d
|
||||
```
|
||||
|
||||
Then back in your normal shell type:
|
||||
|
||||
```sh
|
||||
# On a mac
|
||||
open world.png
|
||||
# On windows
|
||||
start world.png
|
||||
```
|
||||
|
||||
Or navigate to your base directory and open world.png and the result should look like this: ![world.png]
|
||||
|
||||
|
||||
### Step 3
|
||||
|
||||
The next logical step is to run the same code as a python script from your shell/terminal. This way you will be able to modify and experiment with the settings.
|
||||
|
||||
This can be done by adding a line at the top of the script like:
|
||||
|
||||
```sh
|
||||
#!/usr/bin/env python
|
||||
```
|
||||
|
||||
Copy this entire text below and save as a file called world.py.
|
||||
|
||||
```python
|
||||
#!/usr/bin/env python
|
||||
|
||||
import mapnik
|
||||
m = mapnik.Map(600,300,"+proj=latlong +datum=WGS84")
|
||||
m.background = mapnik.Color('steelblue')
|
||||
s = mapnik.Style()
|
||||
r=mapnik.Rule()
|
||||
r.symbols.append(mapnik.PolygonSymbolizer(mapnik.Color('#f2eff9')))
|
||||
r.symbols.append(mapnik.LineSymbolizer(mapnik.Color('rgb(50%,50%,50%)'),0.1))
|
||||
s.rules.append(r)
|
||||
m.append_style('My Style',s)
|
||||
lyr = mapnik.Layer('world',"+proj=latlong +datum=WGS84")
|
||||
lyr.datasource = mapnik.Shapefile(file='/Users/path/to/your/data/world_borders')
|
||||
lyr.styles.append('My Style')
|
||||
m.layers.append(lyr)
|
||||
m.zoom_to_box(lyr.envelope())
|
||||
mapnik.render_to_file(m,'world.png', 'png')
|
||||
```
|
||||
|
||||
* Don't forget to change the path to your world_borders shapefile.
|
||||
* Note: Mapnik accepts both the absolute path to your data as well as the relative path
|
||||
* Note: Same goes for the path to where you want to save your file
|
||||
|
||||
Next make the script executable. On Mac or Linux you would do this with the command:
|
||||
|
||||
|
||||
```sh
|
||||
chmod +x world.py
|
||||
```
|
||||
|
||||
Finally run the script with the command:
|
||||
|
||||
|
||||
```sh
|
||||
# You must be in the same directory as you saved the script
|
||||
./world.py
|
||||
# Add a second optional command to open the resulting file with one keystroke
|
||||
# On a mac
|
||||
./world.py; open world.png
|
||||
# On windows
|
||||
start world.py && start world.png
|
||||
```
|
||||
|
||||
* Run this way the script will continually write over and open the world.png map.
|
||||
* Now you can easily open the script in a separate text editor and try changing the dimensions, colors, or datasource (remember to use the correct projection).
|
||||
|
||||
To download this script along with other tutorial scripts see: http://code.google.com/p/mapnik-utils/
|
||||
[[Getting started using XML|GettingStartedInXML]]
|
||||
[[Getting started using Python|GettingStartedInPython]]
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue