Which of these ruby and python should I use?

I had had been concerning which of these I use.
and I decided ruby.
but I'm really not sure which I should use.
things I wanna do:
Raspberry Pi,
create web app, Android app, iphone app,

and I'm into Machine learning, computer network, security and math.
currently I'm good at java.

so which of these would be better for me to choose.

Added (1). Let me know the reason too!

Python is likely good