How to install python 2 alongside python 3 with conda and install opencv

Create a new environment names pyth2 for installing python2. 

conda create --name pyth2 python=2
 
To check envs:

conda info --envs

After that you can switch environment in conda by:

In Windows: 

activate pyth2

In Linux: 

source activate pyth2
 
Then if you want to install opencv in pyth2 environment, run: 

conda install -c https://conda.anaconda.org/menpo opencv3 
 
To check installation:

import cv2 cv2.__version__