title: how are vectors, matrices, and data frames implemented in R?
body: <p>I've been trying to learn about the different data structures used in popular languages that I have experience with such as lists and dictionaries in Python, associative arrays in PHP (essentially hash tables), vectors in C++, etc.</p>
  
  <p>I have a lot of colleagues that use R religiously and I was wondering how vectors, matrices, and data frames are implemented in R. What are their strengths and weaknesses? I was looking through source code but I couldn't find the data structures themselves. Where in the source code are these definitions located?</p>