Student or Learner
Are opposite and in the opposite of interchangeable?
1. The shop is in the opposite of the library.
2. The shop is opposite the library.
If yes, which one is more in common use than another one as I see the first usuage always.
You asked a very similar question in the Ask a YTeacher forum yesterday. Didn't you find the answers you got helpful?
As for this question, I don't understand how you 'see the first usage always' when it makes no sense whatsoever.
2. is a correct sentence, but it is neither an idiom nor a saying.