How can I install opencv for python?

Answer 1

That can be a pain in the neck, indeed...

What OS you are running?

Answer 2

It's not that simple, you can't just pip install it like you'd normally do. It has to be compiled for Android, which makes it not that simple to achieve.

You might either try downloading a package from here:
http://qpypi.qpython.org:11000/simple/opencv-qpython/
or use sl4a built-in libraries to manage the camera vision.