All-pass filter implementation in numpy
The Hibert transform will produce a signal with 90 degree phase shift.  Look in Numpy documentation at scipy.signal.hilbert as a start.

I'm not sure what you are actually trying to do, but you mentioned 90 degree phase shift and radio in the same post, so you may find the following article of use:

http://home.comcast.net/~szemengtan/LinearSystems/hilbert.pdf