How to install OpenCV 3.1 for Python 3.5 On Ubuntu 16.04 LTS?

I found this.

OpenCV on wheels.

Unofficial OpenCV packages for Python.

Installation was painless for Ubuntu 16.04:

pip3 install opencv-python

Check the installation:

python3
Python 3.5.2 (default, Nov 17 2016, 17:05:23) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.__version__
'3.2.0'

python3-opencv can be installed from the Universe repository in Ubuntu 17.10 and later. Open the terminal and type:

sudo apt install python3-opencv  

Upgrade your OS to 18.04 if you are using Ubuntu 14.04 or Ubuntu 16.04. If Ubuntu 16.04 is installed in WSL sudo do-release-upgrade will upgrade it to 18.04.

I have OpenCV version 3.1 on Ubuntu 16.04 LTS to work with Python 3.5.1. At the latest version it's fixed, try:

http://cyaninfinite.com/tutorials/installing-opencv-in-ubuntu-for-python-3/

But I didn't download dev python and OpenCV, I took directly from github:

EDIT:

Here are the instructions I tested successfully and mentioned in the link above:

1. Update the repository: sudo apt-get update

2. Download the required packages to compile OpenCV:

   sudo apt-get install build-essential cmake git libgtk2.0-dev pkg-config libavcodec-dev libavformat-dev libswscale-dev
   

3. Install the developer packages for Python3.5: sudo apt-get install python3.5-dev
4. Copy the dev files:python3.5-config --includes The output should be similar to: -I/usr/include/python3.5m -I/usr/include/x86_64-linux-gnu/python3.5m. The first part of the output is the expected location & the second part shows the current location of the config file. To solve this problem, we’ll copy the file from the current location to the expected location: sudo cp /usr/include/x86_64-linux-gnu/python3.5m/pyconfig.h /usr/include/python3.5m/
5. Create a temporary directory, move into it and run: git clone https://github.com/Itseez/opencv.git. This will download OpenCV 3. Then rename the folder opencv to opencv-3

6. Create a build directory, move to it and run:

   cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local ../opencv-3
   

7. After the process is finished, run make and then sudo make install.
8. Enjoy.