Develop Reference

Error importing cv2 in Python after opencv installation

I've successfully installed OpenCV, but when I try to import it in Python, I get the errors below.
In Python 2.7, I'm getting this
[imukunya#li165-244 site-packages]$ python
Python 2.7.5 (default, Oct 30 2018, 23:45:53)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-36)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> 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
In Python 3.6, I'm getting this error
[imukunya#li165-244 site-packages]$ python3.6
Python 3.6.5 (default, Apr 10 2018, 17:08:37)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: dynamic module does not define module export function (PyInit_cv2)
I've already tried installing NumPy using $~python3 -m pip install numpy -I

Please try to execute the below command. Then please verify whether your code is working.
python -m pip install opencv-contrib-python

How do I install shogun's python interface?

I'm on a Mac. Step 1:
sudo conda install -c conda-forge shogun
Step 2:
$ python
Python 2.7.12 |Anaconda custom (x86_64)| (default, Jul 2 2016, 17:43:17)
[GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
Anaconda is brought to you by Continuum Analytics.
Please check out: http://continuum.io/thanks and https://anaconda.org
>>> import shogun
>>> from shogun import RealFeatures, PolyKernel, CSVFile
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: cannot import name RealFeatures
I also tried on Fedora using the RPMs. After verifying that the C++ interface works (gcc shogun.cpp -I/usr/include/shogun/base -lshogun -L/usr/lib64/libshogun.*) I followed the instructions here and set PYTHONPATH=/usr/lib64/python2.7/site-packages/modshogun.py
And then:
$ python
Python 2.7.13 (default, May 10 2017, 20:04:36)
[GCC 6.3.1 20161221 (Red Hat 6.3.1-1)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import shogun
>>> from shogun import RealFeatures, PolyKernel, CSVFile
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: cannot import name RealFeatures

The problem here is probably that shogun's docs are currently for the in-development version 6.1, but the conda package is for the latest actual release 6.0. In 6.0, you need to do from modshogun import RealFeatures; the shogun package is the old interface, and the modern "modular" one is modshogun. This will be renamed to just shogun in the upcoming 6.1 release.

Installing rpm and yum in anaconda python on centos 7

How do I install the redhat yum packages within an anaconda environment on CentOS? These packages exist in the standard Centos dist:
$ lsb_release -d
Description: CentOS Linux release 7.3.1611 (Core)
$ python
Python 2.7.5 (default, Nov 6 2016, 00:28:07)
Type "help", "copyright", "credits" or "license" for more information.
>>> import rpm
>>> import yum
>>> print(rpm.__package__, rpm.__file__, rpm.__path__,rpm.__version__)
('rpm', '/usr/lib64/python2.7/site-packages/rpm/__init__.pyc', ['/usr/lib64/python2.7/site-packages/rpm'], '4.11.3')
>>> print(yum.__package__, yum.__file__, yum.__path__,yum.__version__)
('yum', '/usr/lib/python2.7/site-packages/yum/__init__.pyc', ['/usr/lib/python2.7/site-packages/yum'], '3.4.3')
I can't find similar packages (in the ways that I know) for anaconda:
$ source anaconda3/bin/activate python2.7
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
Anaconda is brought to you by Continuum Analytics.
Please check out: http://continuum.io/thanks and https://anaconda.org
>>> import rpm;
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named rpm
>>> import yum
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named yum
>>>
pip and conda search don't seem to have these packages either.

When you run source
anaconda3/bin/activate python2.7
you are running python2.7 using a different virtual environment, where the package repository is different. You should source into the venv and install the packages there.

How do I get Python to see libtorrent-rasterbar in mac os?

I try to install libtorrent-rasterbar, but Python does not see the module. The El Captaine system. Tell me where to look?
andrew: ~ $ brew install python3
Warning: python3-3.6.0_1 already installed
andrew: ~ $ brew install libtorrent-rasterbar
Warning: libtorrent-rasterbar-1.1.1 already installed
andrew: ~ $ python
Python 3.6.0 (default, Mar 4 2017, 12:32:37)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import libtorrent
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'libtorrent'
>>>

For python2 it work: https://gist.github.com/jacobzelek/ecb6e98feb91d911e231
May be for python3 is similarly

Not able to import readline in django shell python

I am on Centos 6 Linux
When i try this
Python 2.7.3 (default, Nov 23 2012, 18:02:22)
[GCC 4.4.6 20120305 (Red Hat 4.4.6-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> import readline
Traceback (most recent call last):
File "<console>", line 1, in <module>
ImportError: No module named readline
>>>
I try to install python readline with pip and i get this
virtualenv/bin/pip-2.7 install readline
Requirement already satisfied (use --upgrade to upgrade): readline in ./virtualenv/lib/python2.7/site-packages/readline-6.2.4.1-py2.7-linux-x86_64.egg
Cleaning up...
what should i do
EDIT:
I tried this as well
[myhost]$ virtualenv/bin/python2.7
Python 2.7.3 (default, Nov 23 2012, 18:02:22)
[GCC 4.4.6 20120305 (Red Hat 4.4.6-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import readline
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named readline
>>>
I tried all that
(virtualenv)[aaaaaa]$ source virtualenv/bin/activate
(virtualenv)[aaaaaa]$ virt
virtualenv/ virtualenv-clone virtualenvwrapper.sh
virtualenv-2.7 virtualenvwrapper_lazy.sh virt-what
(virtualenv)[aaaaaa]$ virtualenv/bin/pip
pip pip-2.7
(virtualenv)[aaaaa]$ virtualenv/bin/pip install readline
Requirement already satisfied (use --upgrade to upgrade): readline in ./virtualenv/lib/python2.7/site-packages/readline-6.2.4.1-py2.7-linux-x86_64.egg
Cleaning up...
(virtualenv)[aaaaa]$ python
Python 2.7.3 (default, Nov 23 2012, 18:02:22)
[GCC 4.4.6 20120305 (Red Hat 4.4.6-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import readline
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named readline
>>>
I tried all vitual env and activating as well. But again i get same error

You need to actually activate the environment you want to use, not just run the python binary from the enviroments bin folder:
$ source /path/to/envirn/bin/activate
$ pip install readline
$ python
> import readline

A workaround that worked for me is to re-install readline:
$ source /path/to/env/bin/activate
$ pip uninstall -y readline
Uninstalling readline-6.2.4.1:
Successfully uninstalled readline-6.2.4.1
$ pip install readline
Collecting readline
Installing collected packages: readline
Successfully installed readline-6.2.4.1