Numpy should be installed when on 20.04

[PeterMitrano]

Thanks for maintaining these scripts, they're so helpful! One small problem with the 20.04 install though, on a clean system where python2 is not installed, this scripy does not install numpy, and so the configuration step of openrave will fail because the test pybind11 program (which includes numpy) will fail.

I would suggest:

1. automatically running pip2 install --user numpy
2. prompting the user to setup alternatives for python2, because otherwise this script will cause python to default to python2, which on 20.04 is probably not what anyone wants. See this blog post for what I mean by "setup alternatives" https://www.fosslinux.com/39384/switching-between-python-2-and-3-versions-on-ubuntu-20-04.htm

[nicholasadr]

Thanks @PeterMitrano for raising this and the suggestions provided. If I understood correctly, the issues that are raised include:

• numpy is not installed for python2
• python defaults to python2, which goes against the default arrangement in Ubuntu 20.04

What do you think of this @leonardoedgar? Some of my thoughts:

• briefly looking at install-dependencies.sh, it seems that you had included numpy installation for 20.04
• i do agree that for 20.04, python preferably calls python3 and to call python2 explicitly with python2?

[leonardoedgar]

Hi @nicholasadr, I briefly tested for the issues mentioned above. The results are as the following:

• Numpy v1.6.16 is installed and importable with python2. However, for python3, numpy is not installed since it is not needed. I believe this is the behaviour that we want.
• Calling python in the command line will direct to python2 interpreter instead of python3. I agree that it would be better to change the default python call to call python3 interpreter instead of python2.