OSError geos_c could not be found when Installing Shapely

Question

I'm a newbie to making/plotting on maps with python, been trying to follow this blogpost to generate a world map (http://sciblogs.co.nz/seeing-data/2011/08/12/plotting-geographic-data-on-a-world-map-with-python/). Got stuck with a few things here:

1. Installing Basemap (a Matplotlib extension for plotting data on geographic projections).

   from mpl_toolkits.basemap import Basemap
   Traceback (most recent call last):
   File "geos_demo.py", line 1, in <module>
   from mpl_toolkits.basemap import Basemap
   ImportError: No module named mpl_toolkits.basemap
   

2. Install Shapely, but the following error occurs [1]:

3. Then I went into the geos.py file and change all the references of geos.dll to geos_c.dll, as recommended by the link here: http://osgeo-org.1560.n6.nabble.com/osgeo4w-258-Problems-with-python-shapely-python-2-7-2-td4336816.html

4. However, the same error [1] occurs.

I'm using Python 2.7.1 and Mac OS 10.7.4. Please let me know if I can provide additional information, and really appreciate any guidance from the community here! Thanks!

[1]

    from shapely.geometry import Point
    Traceback (most recent call last): File "<stdin>", line 1, in <module>
    File "/Users/Desktop/python/ENV/lib/python2.7/site-packages/shapely/geometry/__init__.py", line 4, in <module>
    from geo import box, shape, asShape, mapping
    File "/Users/Desktop/python/ENV/lib/python2.7/site-packages/shapely/geometry/geo.py", line 5, in <module>
    from point import Point, asPoint
    File "/Users/Desktop/python/ENV/lib/python2.7/site-packages/shapely/geometry/point.py", line 7, in <module>
    from shapely.coords import required
    File "/Users/Desktop/python/ENV/lib/python2.7/site-packages/shapely/coords.py", line 8, in <module>
    from shapely.geos import lgeos
    File "/Users/Desktop/python/ENV/lib/python2.7/site-packages/shapely/geos.py", line 59, in <module>
    _lgeos = load_dll('geos_c', fallbacks=alt_paths)
     File "/Users/Desktop/python/ENV/lib/python2.7/site-packages/shapely/geos.py", line 44, in load_dll
    libname, fallbacks or []))
    OSError: Could not find library geos_c or load any of its variants        ['/Library/Frameworks/GEOS.framework/Versions/Current/GEOS', '/opt/local/lib/libgeos_c.dylib']

Answer 1

For questions 2-4, you have to have GEOS installed on your system. If you have homebrew you can do the following:

brew install geos

Install homebrew here if you don't have it: http://mxcl.github.com/homebrew/

Answer 2

On Ubuntu, to install GEOS, this worked for me:

$ sudo apt-get install libgeos-dev

Answer 3

With OS X 10.11 (El Capitan) and Boxen, I had do do this:

brew install geos
sudo mkdir /opt/local
sudo ln -s /opt/boxen/homebrew/lib /opt/local/lib

to let Shapely find libgeos_c.dylib in one of the locations it was willing to look for it.

Answer 4

The problem seems to be that you haven't actually installed the required modules.

Lines of Python code like

from mpl_toolkits.basemap import Basemap

Are import statements that tell your script to use modules (or other bits of Python code) that you need to have already installed.

For each of the packages mentioned (NumPy, Matplotlib, Basemap) you will have to figure out how to install them on your system. In the case of NumPy and Matplotlib this can be complicated because they require compilation. For instance these are theNumpy instructions.

If you just wanted to try playing with the instructions in that blog post then you could use a service like PythonAnywhere which has numpy, matplotlib, and basemap installed already. (disclaimer, I work on PythonAnywhere...)

Answer 5

on windows 10, python 3.6.5 64bit

• install osgeo4w
• add installed folder to PATH e.g. C:\OSGeo4W64\bin (must contain geos_c.dll)
• restart command line

enjoy

Answer 6

I know it is a pretty old question but, as an alternative to https://stackoverflow.com/a/12683010/597743 you could use MacPorts to install the geos library:

port install geos

And the installation steps for MacPorts are described here: https://www.macports.org/install.php