Develop Reference

Installing mesos egg for python 2.7

I've installed mesos 0.26 successfully on a vm machine.
The installation has been performed on an ubuntu trusty thar system
by following this manual:
https://open.mesosphere.com/getting-started/install/
So far so good. I wanted to write a tiny python framwork.
For this I need to install the eggs via easy_install:
(I've downloaded the eggs accordingly for the trusty thar ubuntu and the 0.26 mesos):
wget http://downloads.mesosphere.io/master/ubuntu/14.04/mesos-0.26.0-py2.7-linux-x86_64.egg
easy_install mesos-0.26.0-py2.7-linux-x86_64.egg
all went fine, however, if I start python in the shell
and type in
import mesos.interface
I get the message: ImportError: No module named interface
As someone suggested, it may be that there is no longer a binding for python, or that they have renamed the API calls. Well, I looked in the version updates here:
http://mesos.apache.org/documentation/latest/upgrades/
Since the transition from 0.19.x to 0.20.x there hasn't been any changes regarding the mesos.interface part, or at least they are not mentioning it here.
To increase the confusion I also get the following error message when I'm typing in python: import mesos.native
There I receive: ImportError: No module named interface.mesos_pb2. To put it into a nutshell: what is going wrong here, and how can it be fixed? And yes, I've googled various web pages, with terms such as "mesos python bindings", mesos +api +python, etc. And yes, I have also consulted the official mesos webpage. There are nice refences for Java and C++ but not for python, or at least they are very well hidden.
Thanks in advance for any hints.

Solved. For what reasons ever:
export PYTHONPATH=${PYTHONPATH}:/usr/lib/python2.7/site-packages/
is required to set the PYTHONPATH. After that step it works like a charm.

How to make downloaded Python libs work on Windows?

I got this simple problem and I can't find the answer anywhere, I'm wasting a lot of time!
I did a Python programm on Linux (which works OK), but when I try to run it on Windows, there are too problems with libs...
I have installed the libs I need (dateutil, lxml, xmlrpclib...) in C:\Python34\Lib\site-packages. But then, they don't work as they do on Linux. For example:
from dateutil.tz import tzlocal
Gives me next error:
File "C:\Python34\lib\site-packages\dateutil\tz.py", line 9, in module
from six import string_types, PY3 ImportError: No module named 'six'
That is, they are not finding the other modules... why???

Have you try this ?
http://www.instructables.com/id/How-to-install-Python-packages-on-Windows-7/
Maybe it can help

It looks like you're using Python 3.4 which comes with pip. pip is a tool for installing packages and any dependencies they might have (like the srting_types module from your error message). I'd suggest learning how to use it because it resolves most of the packaging problems with you needing to moving things around yourself. See an answer from a different question to learn more about pip.
There are some packages that need to be compiled. This can be difficult on Windows 7 if you don't have the proper toolchain set up to compile packages. I'd recommend Christoph Gohlke's wonderful collection of installable packages for Windows. You just need to make sure to grab the right version. Since 3.4 is still relatively new, some packages may not be available, so be warned.

ImportError: Permission Denied while using LXML

I've been having a ton of trouble using LXML, after installing it from https://pypi.python.org/pypi/lxml/3.2.1 using Easy_Install-2.7. I installed it on Windows using cygwin, and at first the package seemed to be okay. However upon further testing I ran into problems.
When I run code with:
import lxml
it works completely fine. But as soon as I try:
import lxml.etree
I get this error:
Traceback (most recent call last):
File "D:\Nick_Code\NewsScraper\testdummy.py", line 7, in <module>
import lxml.etree
File "/usr/lib/python2.7/site-packages/lxml-3.2.0-py2.7-cygwin-1.7.20-i686.egg/lxml/etree.py", line 7, in <module>
__bootstrap__()
File "/usr/lib/python2.7/site-packages/lxml-3.2.0-py2.7-cygwin-1.7.20-i686.egg/lxml/etree.py", line 6, in __bootstrap__
imp.load_dynamic(__name__,__file__)
ImportError: Permission denied
I've been trying to find information/work arounds for quite a while but no success. Please let me know if you have any insight or need information.
Thanks!
Michael

This is not a solid answer. But I will highlight several of the problems involved for obtaining a solution. Most likely the problem above, is like a cancer caused by several factors acting catastrophically together.
I have the same exact problem as in the OP, when attempting to use the native Cygwin supplied Python packages on my Windows Vista machine. Being new to Python I have spent several days in trying to get this to work, and understand why it is not working. But all my Google-fu returned nothing but countless dead ends. So here's my take on this.
There are many reasons why Python could have trouble under Cygwin, some which you can do something about and some which are beyond most peoples control. What it boils down to, are the following key issues:
Windows is a complete mess when it comes to file permissions, and Cygwin cannot handle windows file permissions very well. So what you see in Cygwin is far from the whole story.
Windows is shamefully character case-independent which causes loads of trouble, especially when you need to (cross)compile anything that was originally developed under *nix based system (i.e. everything). In fact, if you attempt extracting any archive that contains files whose names differ only in capitalization. (I.e. "makefile" vs "Makefile" etc.) files under Windows or Cygwin, you loose all but one of the files. in case their You need to enable case-sensitivity to do anything more than "hello world" *nix compilations.
Windows handles symlinks completely different than Cygwin. And if your ZIP, TAR etc. archives contain any symlinks, they will be broken after extraction to Windows environment.
Sloppy code practices, where developer have not properly tested their creations on various environments, or carefully set proper file permissions to their *.tar.gz collections. Including correct dependency specifications, or mentioning whether or not binaries has been statically linked etc.
For the full gory details and further (Win-Cygwin) issues, look HERE.
At first I tried to use Cygwin's own Python without any additional packages, and nstalling lxml using PIP and easy_install. Then I tried to use Cygwin's own libxml2, libxslt and xml python packages, and I had the same problems.
At first, after installing the static windows binaries (as suggested elsewhere),
I got this error:
File "/usr/lib/python2.7/site-packages/lxml-3.2.4-py2.7-cygwin-1.7.24-i686.egg/lxml/etree.py", line 6, in __bootstrap__
imp.load_dynamic(__name__,__file__)
ImportError: Permission denied
Aborted (core dumped)
Then I investigated the file permissions and changed those with: chmod -R 755 /usr/lib/python2.7/
I got one step further to isolate problem to an apparently missing file.
And enabling verbose and diagnostic mode's didn't help much either.
File "/usr/lib/python2.7/site-packages/lxml-3.2.4-py2.7-cygwin-1.7.24-i686.egg/lxml/etree.py", line 6, in __bootstrap__
imp.load_dynamic(__name__,__file__)
ImportError: No such file or directory
Aborted (core dumped)
HERE is the exact statement specification:
Load and initialize a module implemented as a dynamically loadable shared
library and return its module object. If the module was already initialized, it
will be initialized again. Re-initialization involves copying the __dict__
attribute of the cached instance of the module over the value used in the module
cached in sys.modules. The pathname argument must point to the shared library.
The name argument is used to construct the name of the initialization function:
an external C function called initname() in the shared library is called. The
optional file argument is ignored. (Note: using shared libraries is highly
system dependent, and not all systems support it.)
So I started reading on the lxml website which clearly state lxml's dependencies on both libxml2 and libxslt, and unless they are statically linked, they also depend on iconv and zlib. So you're lead to believe you need to install all of these. Don't! Continue reading. But if you're going to build from sources (as easy_install may try to do) you'll need everything, including the development header libraries: libxml2-devel, libxslt-devel. Another place states that you also need Cython and install with:
easy_install lxml==dev
The dependencies are shown in this picture from HERE:
So you think you may get away with something like:
STATIC_DEPS=true pip install lxml
But that doesn't do it either. Probably because the libraries used to compile Cygwin's Python have to be the same as those for compiling lxml. But I don't know. Notice how the lxml package refers to Cygwin "1.7.24". My Cygwin is already "1.7.25" and you can check this with uname -a. Then you can check your static python executable with file and ldd. Then you understand that this also depend on the C-compiler used for building python/cygwin under Windows or *nix. Smelling a nightmare I decided that building my own was not the way to go. So next I tried to install the Python libraries (supplied as
executables) meant for Windows Python. This didn't work since I never had windows native Python installed, and I was greeted with an error that the installed could not find Python in my registry. I could of course just extract the executable, but I wouldn't know where to put the binaries without the installer. So I had another idea...
There are 3 possible solutions to getting this to work, as far as I can see.
The easy way of installing a Windows native Python interpreter. You loose some native Cygwin functionality, unless you install in correct place: /usr/lib/python2.7 and make sure Cygwin can find it and use it. This also uses a different file-permissions, case-sensitivity and character set (UTF-16LE) than Cygwin (UTF-8), potentially creating many other issues down the line! Difficulty: Easy
Continue hacking the Cygwin's Python, to make it work with the binary libraries used in (1). But this requires:
a) Uninstall and remove all Cygwin Python packages, except bare Python interpreter.
b) Remove all PIP and easy install traces.
c) Hacking the Windows registry to pretend to have Python27 installed:
HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.7\InstallPath C:\Python27\
HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.7\PythonPath C:\Python27\Lib;C:\Python27\DLLs;C:\Python27\Lib\lib-tk
HKEY_CLASSES_ROOT...
d) Install the Windows binary libraries.
e) All the rest should now hopefully work with PIP or easy_install. Difficulty: Medium!
Doing it properly by compiling Python and all libraries from scratch. Difficulty: Hard!
I successfully did (1), but I still think (2) is the smarter way of doing it, but I have not tested it, which is why I don't consider this as a good answer. BTW. One more quirk, I have to run the interpreter with: python.exe -E to avoid an annoying: "SyntaxError: invalid syntax" when hitting return!
Conclusion:
Apparently, you don't need the libxml2 and libxslt python packages to use lxml!
In my case I needed Scrapy, so I also had to install a few other packages.
$ pip.exe list
cssselect (0.9.1)
lxml (3.2.4)
pip (1.4.1)
pyOpenSSL (0.11)
pywin32 (218)
queuelib (1.1.1)
Scrapy (0.20.0)
setuptools (1.4.1)
six (1.4.1)
Twisted (13.2.0)
w3lib (1.5)
zope.interface (4.0.5)
$ll /cygdrive/c/Python27/Lib/site-packages/
adodbapi
cssselect
isapi
lxml
OpenSSL
pip
pythonwin
pywin32_system32
queuelib
scrapy
twisted
w3lib
win32
win32com
win32comext
zope
cssselect-0.9.1-py2.7.egg-info
lxml-3.2.4-py2.7.egg-info
pip-1.4.1-py2.7.egg-info
queuelib-1.1.1-py2.7.egg-info
Scrapy-0.20.0-py2.7.egg-info
six-1.4.1-py2.7.egg-info
Twisted-13.2.0-py2.7.egg-info
w3lib-1.5-py2.7.egg-info
zope.interface-4.0.5-py2.7.egg-info
PyWin32.chm
setuptools-1.4.1-py2.7.egg
pyOpenSSL-0.11-py2.7.egg-info
pywin32-218-py2.7.egg-info
easy-install.pth
pywin32.pth
setuptools.pth
zope.interface-4.0.5-py2.7-nspkg.pth
pythoncom.py
six.py
pythoncom.pyc
six.pyc
pythoncom.pyo
pywin32.version.txt
README.txt
Useful References:
HERE
HERE
HERE HERE HERE HERE
HERE

How to use OpenCV in Python?

I have just installed OpenCV on my Windows 7 machine. As a result, I get a new directory:
C:\OpenCV2.2\Python2.7\Lib\site-packages
In this directory, I have two files: cv.lib and cv.pyd.
Then I try to use the opencv from Python. I do the following:
import sys
sys.path.append('C:\OpenCV2.2\Python2.7\Lib\site-packages')
import cv
As a result I get the following error message:
File "<stdin>", line 1, in <module>
ImportError: DLL load failed: The specified module could not be found.
What am I doing wrong?
ADDED
As it was recommended here, I have copied content of C:\OpenCV2.0\Python2.6\Lib\site-packages to the C:\Python26\Lib\site-packages. It did not help.
ADDED 2
My environment variables have the following values:
Path=C:\Program Files\MiKTex\miktex\bin;C:\OpenCV2.2\bin;C:\Python26;
PYTHONPATH=C:\OpenCV2.2\Python2.7\Lib\site-packages
Do I need to change something? Do I need to add something?
ADDED 3
I think my question is general: How to use a library? Probably I need to find a *.ddl file somewhere? Then I need to use the name of the directory containing this file as a value to some environment variables? Or maybe I need to use sys.addpath? I also need to know how the way to call the library is related to the name of the file that contains the library.
ADDED 4
It is interesting that when I type import cv, I get:
ImportError: DLL load failed: The specified module could not be found.
But when I type import opencv I get:
ImportError: No module named opencv
ADDED 5
It has been suggested that I usthe e inconsistent version of python. In more details, OpenCV tries to use Python2.7 and I had Python2.6. So, I have installed Python 2.7. It makes difference. Now I do not have the old error message, but I have a new one:
ImportError: numpy.core.multiarray failed to import
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: numpy.core.multiarray failed to import
ADDED 6
I have managed to resolve the problem by installing numpy. It took some time because I did not realized that there are different numpy installer corresponding to different versions of Python. Some details can be found in my answer to my own question (see bellow).

The problem was resolved. The following steps has been done:
A new version of python (version 2.7) has been installed.
After that I still was unable to run OpenCV because I had some problems with the numpy library.
I tired to install numpy but the installer did not see my new version of the Python.
I deleted the old version of Python as well as links to the old version in the Path system vatriable.
After that numpy installer was not able to finish the installation.
I have realized that I need to run another numpy installer that is associated with the Python 2.7. It can be found here.
Finally everything worked. I was able to "import cv".

I suspect you have the same problem I've run into. If you have a 64-bit version of Python, it cannot load 32-bit DLLs. OpenCV currently only ships 32-bit binaries. If you want 64-bit .pyd and .dll files, you have to compile them yourself. There are some instructions on the OpenCV Wiki, but it's not for the faint of heart. Expect to have a substantial time investment.
The easiest solution is to:
Uninstall 64-bit Python
Install a 32-bit distribution.
The PythonXY distribution includes pyopencv -- a good set of OpenCV hooks. The only limitation is that it's 32-bit, so don't make plans to process gigapixel astronomy data with it! ;)
If you must have the 64-bit version, follow these instructions to get it OpenCV to compile with Visual Studio 2010. There's a discussion on stackoverflow that describes building 64-bit apps with VC Express.
EDIT: OpenCV now ships with 64-bit Python binaries. The .dll files need to go somewhere in your path (I put them in the scripts folder), and the .pyd files go in your site-packages directory.

I had trouble interfacing OpenCV with Python, and I was looking all over the place for help. Here's what worked for me. I basically followed this post: http://opencvpython.blogspot.com/2012/05/install-opencv-in-windows-for-python.html. After downloading and extracting OpenCV 2.4.6, you basically get a folder called "opencv" with a bunch of stuff in it. Navigate to build->python->2.7. Inside, there is only one file called "cv2.pyd". I copied this file and pasted it in "python-2.7.5\Lib\site-packages". I'm actually using the Spyder IDE, and it works fine. In the python interpreter, typing in "import cv" worked for me.

Maybe you should edit your environment variable
right click on the "My Computer" or something like this, click on properties.
In the properties window click on the Advanced tab.
Then, the environment variables button.
Change the path.

Has anybody been able to install PyWeka?

I need to install in python 2.6 or 2.7 for windows the library PyWeka0.3dev, It says it requires setuptools, which I installed but then they told me it was a deprecated instalation library and I installed distribute, then I downloaded the PyWeka compressed package and each time I try to install it neither with setup.py nor with easy_install (where it says something like no module ez_setup). Can anybody give me a clue about how to do this?

As mentioned to you via Aardvark (yes, I am omnipresent), the module in question is broken. You can't easy_install it. It's a bug in PyWeka.
You can download the file from PyPI, http://pypi.python.org/pypi/PyWeka/0.3dev, and unpack it.
In the file setup.py, remove the following two lines:
from ez_setup import use_setuptools
use_setuptools()
And install it by running
python setup.py install
You need to have installed numpy and NamedMatrix (which has the same bug as PyWeka) first.
However, you mentioned you are on Windows. I strongly doubt that PyWeka will work on Windows. There are some Unix specific code in it.
And I still really want to know why the authors are reading files by calling cat from subprocess. That seems pretty pointless and is together with the broken install, good enough reason for me to keep far away from that module. I suspect it's authors simply have no idea what they are doing.
That, or they are geniuses.

A punk/goth approach to programming probably has the right to be..
To get the C-compliation part to work on windows you either need (1) to have Visual Studio of the same version that was used to compile the python version you are using, or (2) mingw which is a bit trickier to set up.