sudo apt-get python-opencv fetching different version than expected

sudo apt-get install python-opencv installs a .so file corresponding to opencv2.4.x, but I want the lib corresponding to opencv3.1.

Detailed context:

I am learning openCV3.1. Everything for running a opencv example is complete and when I run a sample python script, which is using a library cv2.so, I realized that the program is giving runtime error because of an incorrect version of cv2.so (cv2.so installed corresponding to 2.4.9 version of openCV, I wanted cv2.so corresponding to 3.1 version). So, I think the issue is in apt-get sources/config files etc which I need help to resolve.

Below content might be useful to understand, Output of sudo apt-get download python-opencv :

Get:1 xenial/universe amd64 python-opencv amd64 2.4.9.1+dfsg-1.5ubuntu1 [310 kB]
Fetched 310 kB in 21s (14.6 kB/s)
W: Can't drop privileges for downloading as file '/home/bhargav/python-opencv_2.4.9.1+dfsg-1.5ubuntu1_amd64.deb' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied)

2 Answers

Well for your information the opencv version in Xenial is only 2.4.9 details as follows :

 python-opencv: Installed: (none) Candidate: 2.4.9.1+dfsg-1.5ubuntu1 Version table: 2.4.9.1+dfsg-1.5ubuntu1 500 500 xenial/universe amd64 Packages

Your require opencv 3.1 , well you need to install a bunch of things which can be found in other blogs. I am not gonna write all those here rather I can show you links because its very well explain over there.Link here. You can follow it in your Ubuntu 16.04.

You can install OpenCv for Python from PyPI (python package index):

1. Uninstall previous version
2. Make sure your pip is up to date: pip install -U pip
3. Install opencv-python: pip install opencv-python
4. import cv2
5. Check version: cv2.__version__

This works also with virtualenvs.