Installing matplotlib on Ubuntu 14.04 after installing Python 3 with pyenv

I dont have Ubuntu system right now with me. but still I can help you I think.

open your terminal and type as

apt-cache search python3-matplotlib

If you find it like its available then you can install it from

sudo apt-get install python3-matplotlib

that is the most preferred way.

Now how to use matplotlib with python 3. I have posted a question also in here about how to use python2 and python3 side by side.

Simple , use python3 <filename.py> while executing your program with python3-matplotlib

and similarly if you use python2 then it will load python 2.

hope that helps.