Who prepares input for R tasks

I am new to R.

Suppose to have some data that we have to parse for maybe building a representation in vectorial space of several items that will have to be clustered; it involves some text processing and manipulation. Other goals of the parsing might be to output a .csv, or a tab separated file. When doing this in Python, I would often use data structures such as dictionaries, sets, hash-maps.. such data structures seems not to be available on R.

I would like to know, do R users usually prepare/build their input data (that will be printed as a .csv or a tab separated file as above pointed out) with R itself, or do they usually rely on other programming languages more powerful for doing it, like Python?

At first glance, it seems to me that R is quite assuming that suitable input data are already available in right format, and we are not going to use R also for parsing some source to build a more structured input.