Hi! I'm trying to solve a computational problem and of course speed and size is important there. Apart from picking the right algorithm, I came across an idea that could help speed up things and keep memory requirements down. What I have is regions described by min and max coordinates. At first, I just modeled these as a simple class containing two values for each axis.
In a second step, I derived this class from tuple instead of object. Some code then moved from __init__ to __new__ and some code that modified these objects had to be changed to replace them instead. The upside to this is that they can be used as keys in sets and dicts, which isn't the case for mutable types[1]. What I'm now considering is to only allow a single instance of these objects for each set of values, similar to interned strings. What I would gain is that I could safely compare objects for identity instead of equality. What I'm not yet sure is how much overhead that would give me and/or how to keep it low. The idea is to store each instance in a set and after creating a new object I would first look up an equal object in the global set and return that instead, otherwise add the new one. The problem I foresee is that if I define equality as identity, this lookup when creating will never eliminate duplicates. If I only fall back to equality comparison for non-identical objects, I would probably sacrifice most of the gain. If I build a dict mapping between the values and the actual objects, I would have doubled the required memory and uselessly store the same values twice there. Am I looking in the wrong direction? Is there some better approach? Please don't tell me to use C, as I'm specifically interested in learning Python, I'm pretty sure I could have solved the problem quickly in C++ otherwise. Other suggestions? Cheers! Uli [1] Somebody correct me if I'm wrong, but I believe I could have defined a hashing function for the type and thus allowed its use in a set or dict, right? However, goofing up because you accidentally modified an object and changed its hash value is something I don't want to risk anyway. -- http://mail.python.org/mailman/listinfo/python-list
