Develop Reference

MacOS, c++ python extension cannot find a dynamic library

I'm building a c++ python extension. So far, I created versions for Linux and Windows. Currently, I'm struggling with the MacOS version. CMake produces 2 libraries:
43898860 Aug 29 13:40 libslide_io.dylib
214876 Aug 29 13:40 slideio.cpython-35m-darwin.so
I pack them to a whl file. After installation with pip, when I try to import the package, I'm getting the following error:
(sld-35)dist % python -c "import slideio"
Traceback (most recent call last):
File "<string>", line 1, in <module>
ImportError: dlopen(/Users/.../opt/anaconda3/envs/sld-35/lib/python3.5/site-packages/slideio.cpython-35m-darwin.so, 2): Library not loaded: libslide_io.dylib
Referenced from: /Users/.../opt/anaconda3/envs/sld-35/lib/python3.5/site-packages/slideio.cpython-35m-darwin.so
Reason: image not found
Both libraries are correctly placed to the python environment directory:
/Users/.../opt/anaconda3/envs/sld-35/lib/python3.5/site-packages/
Moreover, if I unzip the whl file and import the package from the current directory, it works.
I suspect that it is something with rpath settings in my cmake files, but cannot find the correct solution. All my attempts are failed.
I would appreciate any help.

If somebody is interested. I solved the problem by adding a post-build with the execution of install_name utility with the #loader_path parameter. The command instructs the system looking for the library at the loader (in my case - the python package) folder.
if (APPLE)
add_custom_command(TARGET ${BINDLIB_NAME}
POST_BUILD COMMAND
${CMAKE_INSTALL_NAME_TOOL} -change libslide_io.dylib #loader_path/libslide_io.dylib
$<TARGET_FILE:${BINDLIB_NAME}>)
endif()

Failed to load GLFW3 shared library on Windows

I am trying to run python code which imports GLFW3 library. It gives this error:
''' File ".\run_simulation.py", line 15, in
from modules.graphics.simulator_visualizer import SimulatorVisualizer File
"F:\webapp\p1_aksu_rubius\utils..\modules\graphics\simulator_visualizer.py",
line 2, in
import glfw File "C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\site-packages\glfw__init__.py",
line 34, in < module>
raise ImportError("Failed to load GLFW3 shared library.") ImportError: Failed to load GLFW3 shared library. '''
I use Windows Server 2012 R2 and Python version 3.7.4 (64 bit)
I found that there is glfw3.dll file in the directory C:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\site-packages\glfw. Then I add this path into Windows environment variable - PATH. Anyway is does not help. What is the problem?
Thanks!

If the .dll is there (it's in the right place), then it was found. Adding its path to %PATH% won't do anything. It's one (at least) of its dependencies that's missing.
According to [PyPI]: GLFW:
Windows
The GLFW shared library is included in the Python wheels for Windows, but the correct Microsoft Visual C++ Redistributable will be required:
VC 2010 for 32-bit Python, or
VC 2012 for 64-bit Python.
So, you need [MS]: Visual C++ Redistributable for Visual Studio 2012 Update 4 (x64). Select VSU_4\vcredist_x64.exe, download, install it and try again.
Let me know how it works out.

Installing Theano with GPU on Windows 8.1 64-bit with Visual Studio 2013 [duplicate]

This question already has answers here:
How do I install theano in Anaconda ver. 2.1 Windows 64 bit for Python 3.4?
(3 answers)
Closed 6 years ago.
This Theano Installation is making me mad :(
So, I've followed the instructions here on the most voted answer because it seemed like the most similar condiguration from mine and up-to-date version : Installing theano on Windows 8 with GPU enabled
1- I've installed Cuda v6.5, launched deviceQuery and it works fine.
2- I already have Visual Studio 2013 so I haven't installed Visual Studio 2010
3- > At the time of writing, Theano on GPU only allows working with 32-bit floats and is primarily built for 2.7 version of Python.
So i don't know exactly what is the current state now but I have a friend with the same configuration than mine and he managed to make it work so I guess it's possible. I've installed Python through Anaconda.
4- I've installed MinGW and Cygwin
5- I've fixed msvc9compiler.py
6- Here's the bottleneck : the PyCUDA Installation
Here's what I've done:
- I've used cygwin to extract the pycuda tar file
- I've executed python configure.py through VS2013 x64 Native Tools Command Prompt than configured siteconfig.py as followed:
BOOST_INC_DIR = []
BOOST_LIB_DIR = []
BOOST_COMPILER = 'gcc43'
USE_SHIPPED_BOOST = True
BOOST_PYTHON_LIBNAME = ['boost_python']
BOOST_THREAD_LIBNAME = ['boost_thread']
CUDA_TRACE = False
CUDA_ROOT = 'C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v6.5'
CUDA_ENABLE_GL = False
CUDA_ENABLE_CURAND = True
CUDADRV_LIB_DIR = ['${CUDA_ROOT}/lib', '${CUDA_ROOT}/lib/x64']
CUDADRV_LIBNAME = ['cuda']
CUDART_LIB_DIR = ['${CUDA_ROOT}/lib', '${CUDA_ROOT}/lib/x64']
CUDART_LIBNAME = ['cudart']
CURAND_LIB_DIR = ['${CUDA_ROOT}/lib', '${CUDA_ROOT}/lib/x64']
CURAND_LIBNAME = ['curand']
CXXFLAGS = ['/EHsc', '-DBOOST_NO_TYPEID']
LDFLAGS = ['/FORCE']
I've executed python setup.py build --compiler="msvc" through VS2013 x64 Native Tools Command Prompt
I've executed python setup.py install through VS2013 x64 Native Tools Command Prompt
When I execute the little test in python, here's what's happening:
PS C:\users\jmm\desktop> python test.py
Vendor: Continuum Analytics, Inc.
Package: mkl
Message: trial mode expires in 29 days
Traceback (most recent call last):
File "test.py", line 7, in <module>
a_doubled = (2*a_gpu).get()
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\gpuarray.py", line 471, in __rm
ul__
return self._axpbz(scalar, 0, result)
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\gpuarray.py", line 333, in _axp
bz
func = elementwise.get_axpbz_kernel(self.dtype, out.dtype)
File "<string>", line 2, in get_axpbz_kernel
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\tools.py", line 423, in context
_dependent_memoize
result = func(*args)
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\elementwise.py", line 417, in g
et_axpbz_kernel
"axpb")
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\elementwise.py", line 157, in g
et_elwise_kernel
arguments, operation, name, keep, options, **kwargs)
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\elementwise.py", line 143, in g
et_elwise_kernel_and_types
keep, options, **kwargs)
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\elementwise.py", line 71, in ge
t_elwise_module
options=options, keep=keep)
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\compiler.py", line 251, in __in
it__
arch, code, cache_dir, include_dirs)
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\compiler.py", line 241, in comp
ile
return compile_plain(source, options, keep, nvcc, cache_dir)
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\compiler.py", line 73, in compi
le_plain
checksum.update(preprocess_source(source, options, nvcc).encode("utf-8"))
File "C:\Users\jmm\Anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg\pycuda\compiler.py", line 52, in prepr
ocess_source
cmdline, stderr=stderr)
pycuda.driver.CompileError: nvcc preprocessing of c:\users\jmm\appdata\local\temp\tmp32jnzb.cu failed
[command: nvcc --preprocess -arch sm_30 -m64 -Ic:\users\jmm\anaconda\lib\site-packages\pycuda-2014.1-py2.7-win-amd64.egg
\pycuda\cuda c:\users\jmm\appdata\local\temp\tmp32jnzb.cu --compiler-options -EP]
[stderr:
tmp32jnzb.cu
'C:\Program' n'est pas reconnu en tant que commande interne
ou externe, un programme exécutable ou un fichier de commandes.
]
Could you please tell me why the hell this doesn't work ?

I have written a practical guide for the whole process:
https://my6266blog.wordpress.com/2015/01/21/installing-theano-pylearn2-and-even-gpu-on-windows/
Good luck! It's not that complicated, just follow the steps one by one.

You probably need to add the path to the executables for Visual Studio in your nvcc.profile
(you can find it in your CUDA bin folder. On my system: C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v6.5\bin).
In my case, since I have Visual studio 2010, I added at the end of nvcc.profile:
"compiler-bindir = C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\bin\amd64"

Actually you don't need to install pycuda to get theano working on your windows machine. I'm not an expert but I have Theano installed on Windows 8.1.
This is my laptop config: 64-bit, nvcc/cuda 6.5, Python 2.7.9, WinPython-64bit-2.7.9.3, Windows 8.1, VS2013 and two graphic units (Intel HD Graphics 4600 and NVIDIA GeForce GT 750M).

The process was a pretty big hassle, so here is a tutorial for anyone that is interested:
All of this has been tested using a clean install of Windows 8.1, with nothing else on it, though it should work fine if you don't have a clean install because this will install all the required versions of the software for you.
You need 64-bit windows, 32 bit will not work. You will also need a CUDA compatible graphics card, so if you don’t have one you’re stuck for now, sadly. This means that you need a relatively modern NVIDIA graphics card, AMD will not work (it can run OpenCL but not CUDA because CUDA is lame and proprietary).
I am installing this on Windows 8.1, but I suspect it should all still work on windows 7 as well.
First download WinPython, (make sure to get python 2.7, version 2.7.10.3, this link points to there) and install it TO A PATH THAT DOES NOT HAVE SPACES IN IT. OTHERWISE THINGS BREAK. I made an Other folder in C:\ (C:\Other) and then made a folder named Python27 (C:\Other\Python27) and tell the installer to install it in there.
Once it is done installing, you will need to add it to your path. Press the windows key and type environment variables, then click “Edit the System Environment Variables”, click Environment Variables in the windows that pops up, scroll down to Path, and then append
C:\Other\Python27\python-2.7.10.amd64
Or wherever else you installed WinPython to
Then add a semicolon after it, so you get
C:\Other\Python27\python-2.7.10.amd64;
This is how you add a specific path to the Path variables, in the future, I will just say to add it here and now give specific steps about how to do that. Note that if you update the system path, the current command prompt windows that are open won’t get that update, and you will have to open a new command prompt window to actually have it use the new path.
The purpose of a path is so your command prompt window knows where programs are, because if you call, say
python
in the command prompt, it will look through every folder in your path until it finds a python.exe. If it can’t find any, it will get angry as it typically would if that program didn’t exist.
If you don’t want to clutter your path variable/if your path variable is full, I put a tutorial here about how to make it so your path is just appended to when you open a command prompt window via a text file that stores all the paths, instead of having to edit the environment variable itself, if you are interested.
You then need to add
C:\Other\Python27\python-2.7.10.amd64\DLL;
C:\Other\Python27\python-2.7.10.amd64\Scripts;
to your path as well (again, or wherever else you installed python. For later on I will just say where I installed it and if you installed it somewhere else it should be pretty easy to just tweak the commands accordingly)
Next, install visual studio 2015 community and visual studio 2013, making sure to install all the tools related to c++ development as well (using custom installation, then under Programming Languages). These don’t need to be in a path without spaces, and they probably won’t let you store them anywhere else anyway and that is OK.
Add
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin;
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\amd64;
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib;
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib\amd64;
To your system path.
Install NOT NEWEST DRIVER BECAUSE THEY ARE UNSTABLE, but instead 355.60 because it is known to be very reliable, and new enough. Then install the CUDA toolkit (it’s also okay to store this in a path with spaces, it probably won’t give you the option either, but even if it does, just let it store it in the default place it wants to store it to). Version 6.5 is needed because version 7 and above aren’t supported by pycuda. If you have a GTX 9__ you will need to download CUDA from here instead.
This will probably automatically append
C:\Program Files (x86)\Windows Kits\8.1\Redist\D3D\x64;
C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v7.5\bin;
C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v7.5\libnvvp;
C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;
To your path, if not you will need to do so now.
Those are the only three things that can be stored to paths with spaces (these will be in like Program Files or Program Files (x86)), with everything else be very careful to store them to paths that don’t have spaces.
Download the boost binaries (1_55_0 for 64 bit which is the version this link points to), and run the installer, then select to store them to a path without spaces (I stored them to C:\Other\boost)
Navigate to that directory in the command line, then run
bootstrap.bat
and then when it is done run
.\b2
This will start building, and take a long time, and use a lot of space (about 6 GB).
It will probably say that 8 targets failed, 8 targets were skipped, and 1075 were updated. This is what one should expect, and is not a problem.
Install Git-2.7.0-64-bit to some path without a space in it
Choose to use Git from the Windows Command Prompt, checkout Windows-style, commit Unix-style endings, use Window’s default console window, and do not enable file system caching.
Add
C:\Other\Git\bin;
To your system path
Next, run the installer for VCForPython.
Download pycuda source (pycuda-2015.1.3)
Navigate inside that directory, then run
python configure.py
this will create a file named siteconf.py.
Open this file, and it should look something like
BOOST_INC_DIR = []
BOOST_LIB_DIR = []
BOOST_COMPILER = 'gcc43'
USE_SHIPPED_BOOST = True
BOOST_PYTHON_LIBNAME = ['boost_python-py27']
BOOST_THREAD_LIBNAME = ['boost_thread']
CUDA_TRACE = False
CUDA_ROOT = 'C:\\Program Files\\NVIDIA GPU Computing Toolkit\\CUDA\\v6.5'
CUDA_INC_DIR = ['${CUDA_ROOT}/include']
CUDA_ENABLE_GL = False
CUDA_ENABLE_CURAND = True
CUDADRV_LIB_DIR = ['${CUDA_ROOT}/lib/Win32', '${CUDA_ROOT}/lib/x64']
CUDADRV_LIBNAME = ['cuda']
CUDART_LIB_DIR = ['${CUDA_ROOT}/lib/Win32', '${CUDA_ROOT}/lib/x64']
CUDART_LIBNAME = ['cudart']
CURAND_LIB_DIR = ['${CUDA_ROOT}/lib/Win32', '${CUDA_ROOT}/lib/x64']
CURAND_LIBNAME = ['curand']
CXXFLAGS = []
LDFLAGS = []
modify it so it looks like:
BOOST_INC_DIR = ['C:/Other/boost']
BOOST_LIB_DIR = ['C:/Other/boost/lib64-msvc-12.0']
BOOST_COMPILER = 'msvc'
USE_SHIPPED_BOOST = True
BOOST_PYTHON_LIBNAME = ['boost_python-vc120-mt-1_55']
BOOST_THREAD_LIBNAME = ['boost_thread-vc110-mt-1_55']
CUDA_TRACE = False
CUDA_ROOT = 'C:\\Program Files\\NVIDIA GPU Computing Toolkit\\CUDA\\v6.5'
CUDA_ENABLE_GL = False
CUDA_ENABLE_CURAND = True
CUDADRV_LIB_DIR = ['${CUDA_ROOT}/lib/Win32', '${CUDA_ROOT}/lib/x64']
CUDADRV_LIBNAME = ['cuda']
CUDART_LIB_DIR = ['${CUDA_ROOT}/lib/Win32', '${CUDA_ROOT}/lib/x64']
CUDART_LIBNAME = ['cudart']
CURAND_LIB_DIR = ['${CUDA_ROOT}/lib/Win32', '${CUDA_ROOT}/lib/x64']
CURAND_LIBNAME = ['curand']
CXXFLAGS = ['/DBOOST_PYTHON_STATIC_LIB', '/EHsc']
LDFLAGS = ['/LIBPATH:C:\\Other\\boost\\/lib64-msvc-12.0', '/FORCE']
then run
python setup.py build
followed by
python setup.py install
This should install pycuda for you =)
To install Theano (with GPU enabled), download release 0.7, unzip it, navigate inside it using a command prompt, and then type
python setup.py install
then go and edit system environment variables, and create one named
THEANO_FLAGS
and set it’s value to
device=gpu,floatX=float32
Then open a new command prompt, and if you have completed all of the steps above, this should work well =) You can run the code here to make sure that you are actually running off the GPU.

I was able to get Theano installed on my ASUS K501LX Windows 8.1 laptop, with an NVIDIA GeForce 950M GPU, without any hassle whatsoever. I largely followed Maor's post above from March 29th. I was actually shocked at how easy it was! All I needed was the Community Edition of Visual Studio 2013 and the CUDA 7 Toolkit. I then installed Anaconda 3.4 (I used the latest version that's out there now). The one modification I made to Maor's post was installing mingw, via conda install mingw libpython immediately after installing Anaconda. Also, since I am using Python 3, I had to change the flags parameter in .theanorc.txt to point to C:\Anaconda3\libs.
Upon importing theano, it returned that it was using my GeForce GTX 950M device, and running the theano\misc\check_blas.py check returned no errors and carried out its tests on my GPU.
Happy times!

python opencv dll load failed Missing environment variables?

I want to use Blender 2.72b with OpenCV, so I had to build it for Python3 (I have 3.4.2 installed since Blender is using that too). I'm working on Win7 64bit, so I used a 64bit version of Python and NumPy (Blender too of course). For OpenCV I used 3.0.0-beta.
For building I used CMake 2.8 and Visual Studio 2010 Professional (since I have a student-license > Visual Studio 10 Win64 in CMake).
I followed these instructions (lower ones), modified for python3.
These are my folders:
Target build-folder for CMake (OpenCV.sln executed and build in here too of course):
C:\Users\Gunnar\Desktop\build\
OpenCV-source-folder:
C:\Users\Gunnar\Downloads\opencv\sources\
Python installed here:
C:\Python34\
The build went fine, I adjusted the following before generating with CMake (python2 left blank):
PYTHON3_EXECUTABLE -> C:/Python34/python.exe
PYTHON3_INCLUDE_DIR -> C:/Python34/include
PYTHON3_LIBRARY -> C:/Python34/libs/python34.lib
PYTHON3_NUMPY_INCLUDE_DIRS -> C:/Python34/Lib/site-packages/numpy/core/include
PYTHON3_PACKAGES_PATH -> C:/Python34/Lib/site-packages
BUILD_opencv_python3 -> true
The build-folder has a cv2.pyd at
C:\Users\Gunnar\Desktop\build\lib\Release\
The cv2.pyd got copied to
C:\Python34\Lib\site-packages\
automatically and I copied it to
M:\Programme\blender-2.72b-windows64\2.72\python\lib\site-packages\
If I now open the python IDLE, I get the following error (same in Blender of course):
>>> import cv2
Traceback (most recent call last):
File "<pyshell#0>", line 1, in <module>
import cv2
ImportError: DLL load failed: Das angegebene Modul wurde nicht gefunden.
(in english: DLL load failed: Module not found.)
I'm assuming that I'm missing environment variables (from what I've found googling for it).
Looking into them I have no corresponding entry for PATH and no PYTHONPATH.
My problem now is that I don't know what I need to set there. I never really had to change something in there and I don't know what exactly is needed.
If more information are needed let me know.
EDIT:
I got i working now. I'm not quite sure, which one it did in the end, but I first used
cmd > setx -m OPENCV_DIR C:\Users\Gunnar\Desktop\build
and than edited the PATH-variable with these:
C:\Users\Gunnar\Desktop\build;
C:\Users\Gunnar\Desktop\build\lib\Release;
C:\Users\Gunnar\Desktop\build\x64\Release;
C:\Users\Gunnar\Desktop\build\bin\Release
And right now it works even though I removed all of them...

Help installing cx_Oracle

I'm trying to install the cx_Oracle for Python 2.6, but it is failing. I don't know enough about C or MS Vis. Studio's compiler to even approach fixing it myself.
This is what is output on the command line:
C:\pydev\cx_Oracle-5.0.1>C:\python26\python setup.py install
running install
running build
running build_ext
building 'cx_Oracle' extension
C:\Program Files\Microsoft Visual Studio 9.0\VC\BIN\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -IC:\Oracle\instantclient\sdk\include -IC:\p
ython26\include -IC:\python26\PC /Tccx_Oracle.c /Fobuild\temp.win32-2.6-11g\Release\cx_Oracle.obj -DBUILD_VERSION=5.0.1
cx_Oracle.c
c:\pydev\cx_oracle-5.0.1\StringVar.c(392) : warning C4018: '>' : signed/unsigned mismatch
c:\pydev\cx_oracle-5.0.1\StringVar.c(417) : warning C4018: '>' : signed/unsigned mismatch
c:\pydev\cx_oracle-5.0.1\ObjectVar.c(117) : warning C4018: '<' : signed/unsigned mismatch
c:\pydev\cx_oracle-5.0.1\ObjectVar.c(134) : warning C4018: '<' : signed/unsigned mismatch
c:\pydev\cx_oracle-5.0.1\Variable.c(331) : error C2036: 'void *' : unknown size
c:\pydev\cx_oracle-5.0.1\Variable.c(878) : warning C4244: '=' : conversion from 'sb2' to 'sb1', possible loss of data
c:\pydev\cx_oracle-5.0.1\Variable.c(914) : warning C4018: '<' : signed/unsigned mismatch
error: command '"C:\Program Files\Microsoft Visual Studio 9.0\VC\BIN\cl.exe"' failed with exit status 2
Does anyone have any idea how to fix this?
(I also may have an issue with that cl.exe file, I think I remember seeing this as a problem somewhere else, but I have four Windows machines which could have had issue there.).
----------------------------- EDIT -----------------------------
The reason I do not use the pre-compiled installer is because when I try to run the module I get the following:
Python 2.6.3 (r263rc1:75186, Oct 2 2009, 20:40:30) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import cx_Oracle
Traceback (most recent call last):
File "", line 1, in
ImportError: DLL load failed: The specified module could not be found.
I assume that means that it has not been properly installed. If someone can tell me what I did wrong here, that would also be a perfectly acceptable answer.
----------------------------- EDIT2 -----------------------------
I have retrieved all files from Oracle's Basic Client version 11.1.0.7. I have not tried installing a more substantial client. I am downloading one now.
%ORACLE_HOME%=C:\Oracle\instantclient\ #The directory where the above files have been extracted.
More information
The current directory for the cx_Oracle's setup.py is C:\pydev\cx_Oracle-5.0.1
The version of Python is 2.6.3
The current directory for Python is C:\Python26 -- to access python 2.6 -> type py26 on the command line and it will map to C:\python26\python

Why don't you use a binary package like Windows Installer (Oracle 10g, Python 2.6)?
See http://cx-oracle.sourceforge.net/ for other binary packages
Addendum (as requested): you must ensure to use the cx_Oracle that :
set ORACLE_HOME if this environment variable doesn't exist (see this Oracle FAQ)
python can find oraocci11.dll for Oracle 11g, oraocci10.dll for Oracle 10g or oraclient9.dll for Oracle 9i by adding the folder (should be %ORACLE_HOME%/bin) where the DLL is in you PATH environment variable
use the correct binary package (i.e. built for the right Python/Oracle versions)

You also need some type of Oracle client installed on your machine, since cx_Oracle is just a bridge between Python and the Oracle Client. Valid Oracle Clients include a full Oracle installation (like Standard or XE) or the Instant Client
From the README:
Please note that an Oracle client (or
server) installation is required in
order to use cx_Oracle. If you do not
require the tools that come with a
full client installation, it is
recommended to install the Instant
Client which is far easier to install.
I have not installed on Windows before, but you may have to set the ORACLE_HOME environment variable so that cx_Oracle knows where to look.

If you use Anaconda Python x64, things are easier:
conda install -c https://conda.anaconda.org/anaconda cx_oracle
(It will install the right Oracle client)
If you get the following error:
[Anaconda2] C:\Users\User>conda install -c https://conda.anaconda.org/anaconda c
x_oracle
Using Anaconda Cloud api site https://api.anaconda.org
Fetching package metadata: ......
Solving package specifications: .................
Package plan for installation in environment C:\Anaconda2:
The following NEW packages will be INSTALLED:
cx_oracle: 5.1.2-py27_0
oracle-instantclient: 11.2.0.4.0-0
The following packages will be UPDATED:
conda: 3.19.1-py27_0 --> 4.0.5-py27_0
pip: 8.0.2-py27_0 --> 8.1.1-py27_0
pyyaml: 3.11-py27_2 --> 3.11-py27_3
setuptools: 19.6.2-py27_0 --> 20.3-py27_0
wheel: 0.26.0-py27_1 --> 0.29.0-py27_0
Proceed ([y]/n)? y
Unlinking packages ...
An unexpected error has occurred, please consider sending the | 0%
following traceback to the conda GitHub issue tracker at:
https://github.com/conda/conda/issues
Include the output of the command 'conda info' in your report.
Traceback (most recent call last):
File "C:\Anaconda2\Scripts\conda-script.py", line 4, in <module>
sys.exit(main())
File "C:\Anaconda2\lib\site-packages\conda\cli\main.py", line 173, in main
args_func(args, p)
File "C:\Anaconda2\lib\site-packages\conda\cli\main.py", line 180, in args_fun
c
args.func(args, p)
File "C:\Anaconda2\lib\site-packages\conda\cli\main_install.py", line 45, in e
xecute
install.install(args, parser, 'install')
File "C:\Anaconda2\lib\site-packages\conda\cli\install.py", line 423, in insta
ll
plan.execute_actions(actions, index, verbose=not args.quiet)
File "C:\Anaconda2\lib\site-packages\conda\plan.py", line 538, in execute_acti
ons
inst.execute_instructions(plan, index, verbose)
File "C:\Anaconda2\lib\site-packages\conda\instructions.py", line 148, in exec
ute_instructions
cmd(state, arg)
File "C:\Anaconda2\lib\site-packages\conda\instructions.py", line 95, in UNLIN
K_CMD
install.unlink(state['prefix'], arg)
File "C:\Anaconda2\lib\site-packages\conda\install.py", line 714, in unlink
os.unlink(meta_path)
WindowsError: [Error 5] Access is denied: 'C:\\Anaconda2\\conda-meta\\conda-3.19
.1-py27_0.json'
[Anaconda2] C:\Users\User>
Try running the Anaconda prompt as admin: