How to tell if this girl in my university group likes me?

Im part of a transfer student group at this university and i meet this girl one day. We hung out one day in the library and we both laughed and it seem like she had a good time. She then asked me one night out of the blue if i wanted to go back to the library and write our papers together (we are in the same class). She did invite some people from the group later on after we got there but she told me she didn't expect them to come and hang out with us but she seem to enjoy my company during it and even on the way to class and after.

How to tell if this girl in my university group likes me?
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