matplotlib.pyplot issue python

Question

I'm experiencing a problem with matplotlib, to be more precise with pyplot.

Just after installing, doing

import matplotlib.pyplot

gives me this error:

ImportError: dlopen(/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/_png.so, 2): Symbol not found: _png_create_info_struct
  Referenced from: /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/_png.so
  Expected in: flat namespace
 in /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/_png.so

So I have no idea what is going on. I'm on Mac OS X 10.6, I have installed python2.7 from disk image and matplotlib from the terminal by using the tar.gz and doing the usual

python setup.py build
python setup.py install

When the installation starts I see:

BUILDING MATPLOTLIB
            matplotlib: 1.1.0
                python: 2.7 (r27:82508, Jul  3 2010, 21:12:11)  [GCC 4.0.1
                        (Apple Inc. build 5493)]
              platform: darwin

REQUIRED DEPENDENCIES
                 numpy: 1.6.1
             freetype2: 10.0.4

OPTIONAL BACKEND DEPENDENCIES
                libpng: 1.2.44
               Tkinter: no
                        * TKAgg requires Tkinter
                  Gtk+: no
                        * Building for Gtk+ requires pygtk; you must be able
                        * to "import gtk" in your build/install environment
       Mac OS X native: yes
                    Qt: no
                   Qt4: no
                 Cairo: no

OPTIONAL DATE/TIMEZONE DEPENDENCIES
              datetime: present, version unknown
              dateutil: matplotlib will provide
                  pytz: matplotlib will provide
adding pytz

OPTIONAL USETEX DEPENDENCIES
                dvipng: 1.13
           ghostscript: 8.61
                 latex: 3.1415926

Any help guys please!

Cheers

Answer 1

http://fonnesbeck.github.io/ScipySuperpack/

I've been fighting this same problem and the answer was to install the ScipySuperpack. The problem (at least for me) was that I have a 64 bit version of Python, and the version of matplotlib I was pulling from github was 32 bit. I cloned the ScipySuperpack repository and ran the setup script and it worked.

No amount of fighting with brew or ports was getting me anywhere.

Answer 2

In case anyone has the same problem as me and finds this thread, here is how I solved it.

First, I follow the current matplotlib README.osx, along with this guy's advice (not sure if that's necessary)...

brew install freetype --universal
brew install libpng --universal
export CPPFLAGS="-I/usr/local/opt/libpng/include -I/usr/local/opt/freetype/include"
export LDFLAGS=" -L/usr/local/opt/libpng/lib  -L/usr/local/opt/freetype/lib"

I also set those variables as recommended by brew.

Then, I did the following (running from matplotlib build directory, after having built and installed)

drigz@mbp matplotlib 0$ find . -name _png.so
./build/lib.macosx-10.6-intel-2.7/matplotlib/_png.so
drigz@mbp matplotlib 0$ otool -L ./build/lib.macosx-10.6-intel-2.7/matplotlib/_png.so
./build/lib.macosx-10.6-intel-2.7/matplotlib/_png.so:
        /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.3)
        /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 7.9.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.0)
        /usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 830.0.0)

No libpng! A bad sign... let's see the build output again...

drigz@mbp matplotlib 0$ rm ./build/lib.macosx-10.6-intel-2.7/matplotlib/_png.so
drigz@mbp matplotlib 0$ python setup.py build
[SNIP]
c++ -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk -isysroot /Developer/SDKs/MacOSX10.6.sdk -g -L/usr/local/opt/libpng/lib -L/usr/local/opt/freetype/lib -I/usr/local/opt/libpng/include -I/usr/local/opt/freetype/include build/temp.macosx-10.6-intel-2.7/src/_png.o build/temp.macosx-10.6-intel-2.7/src/mplutils.o build/temp.macosx-10.6-intel-2.7/CXX/cxx_extensions.o build/temp.macosx-10.6-intel-2.7/CXX/cxxsupport.o build/temp.macosx-10.6-intel-2.7/CXX/IndirectPythonInterface.o build/temp.macosx-10.6-intel-2.7/CXX/cxxextensions.o -L/sw/lib -L/usr/local/lib -L/usr/lib -L/usr/X11/lib -lpng14 -lz -lstdc++ -lm -o build/lib.macosx-10.6-intel-2.7/matplotlib/_png.so
ld: warning: in /sw/lib/libpng14.dylib, file was built for i386 which is not the architecture being linked (x86_64)

It's not using the right libpng: what does brew provide?

drigz@mbp matplotlib 0$ echo $LDFLAGS
 -L/usr/local/opt/libpng/lib  -L/usr/local/opt/freetype/lib
drigz@mbp matplotlib 0$ ls /usr/local/opt/libpng/lib 
libpng.a          libpng.la         libpng15.a        pkgconfig
libpng.dylib      libpng15.15.dylib libpng15.dylib

Let's try to fix that by copy-pasting the command but changing -lpng14 to -lpng15... (there's probably a better way to stop it from using the wrong one, but this worked)

drigz@mbp matplotlib 0$ c++ -bundle -undefined dynamic_lookup -arch i386 -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk -isysroot /Developer/SDKs/MacOSX10.6.sdk -g -L/usr/local/opt/libpng/lib -L/usr/local/opt/freetype/lib -I/usr/local/opt/libpng/include -I/usr/local/opt/freetype/include build/temp.macosx-10.6-intel-2.7/src/_png.o build/temp.macosx-10.6-intel-2.7/src/mplutils.o build/temp.macosx-10.6-intel-2.7/CXX/cxx_extensions.o build/temp.macosx-10.6-intel-2.7/CXX/cxxsupport.o build/temp.macosx-10.6-intel-2.7/CXX/IndirectPythonInterface.o build/temp.macosx-10.6-intel-2.7/CXX/cxxextensions.o -L/sw/lib -L/usr/local/lib -L/usr/lib -L/usr/X11/lib -lpng15 -lz -lstdc++ -lm -o build/lib.macosx-10.6-intel-2.7/matplotlib/_png.so
drigz@mbp matplotlib 0$ python setup.py install
[SNIP]
drigz@mbp matplotlib 0$ otool -L /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/_png.so
/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/_png.so:
        /usr/local/opt/libpng/lib/libpng15.15.dylib (compatibility version 29.0.0, current version 29.0.0)
        /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.3)
        /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 7.9.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.0)
        /usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 830.0.0)