Test if point is in some rectangle
Your R-tree approach is the best approach I know of (that's the approach I would choose over quadtrees, B+ trees, or BSP trees, as R-trees seem convenient to build in your case).  Caveat: I'm no expert, even though I remember a few things from my senior year university class of algorithmic!
I have a large collection of rectangles, all of the same size. I am generating random points that should not fall in these rectangles, so what I wish to do is test if the generated point lies in one of the rectangles, and if it does, generate a new point.
Using R-trees seem to work, but they are really meant for rectangles and not points. I could use a modified version of a R-tree algorithm which works with points too, but I'd rather not reinvent the wheel, if there is already some better solution. I'm not very familiar with data-structures, so maybe there already exists some structure that works for my problem?
In summary, basically what I'm asking is if anyone knows of a good algorithm, that works in Python, that can be used to check if a point lies in any rectangle in a given set of rectangles.
edit: This is in 2D and the rectangles are not rotated.