Are any of these quad-tree libraries any good?

问题

It appears that a certain project of mine will require the use of quad-trees, something that I have never worked with before. From what I have read they should allow substantial performance enhancements than a brute-force attempt at the problem would yield. Are any of these python modules any good?

Quadtree 0.1.2 <= No: unable to execute in Python 3.1
QuadTree <= Yes: simple while working with rectangles
quadtree.py <= No: no support for needed operations

EDIT 1: Does anyone know of a better implementation than the one presented in the pygame wiki?

EDIT 2: Here are a few resources that others may find useful for path-finding techniques in Python.

Game Entity Navigation
Catch the Cootie

回答1:

In this comment, joferkington refers to the current question and says:

Just for whatever it's worth, scipy.spatial.KDTree (and/or scipy.spatial.cKDTree, which is written in C for performance reasons) is a far more robust choice than the options listed.

回答2:

Another library to check out is PyQuadTree, a pure python quadtree index that also works on Python 3x. All you need to add an item is its bounding box as a 4-length sequence, so it could be used for a variety of purposes and even negative coordinate systems.

Although I am the author, I really just took someone else's quadtree structure/code and made it more user-friendly, added support for rectangle-quads, and added documentation. A simple example of how to use it:

#SETUP
import pyqtree
spindex = pyqtree.Index(bbox=[0,0,1000,500])

#ADD SOME ITEMS
for item in items:
    spindex.insert(item=item, bbox=item.bbox)

#RETRIEVE ITEMS FROM A REGION
result = spindex.intersect(bbox=[233,121,356,242])

回答3:

The python package index produces 2 other libraries when searching for quadtree : http://pypi.python.org/pypi?%3Aaction=search&term=quadtree&submit=search

disclaimer : never used quadtrees or any of these libraries.

回答4:

Sometimes, it is not obvious how to implement data structures like trees in Python.

For instance,

      D 
    /   \
   B     F
  / \   / \
 A   C E   G

is a simple binary tree structure. In Python, you would represent it like so:

[D,B,F] is a node with a left and right subtree. To represent the full tree you would have:

[D,[[B,A,C],[F,E,G]]]

That is a simple list of nested lists where any node can be a value like D or C, and any node can be a subtree which is, recursively, a list of nested lists. You could do something similar with a dictionary of dictionaries. These types of implementations are a bit quick and dirty and might not be acceptable in an assignment where the instructor expects a Node class with pointers to other nodes, but in the real world it is generally better to use the optimized implementations of Python lists/dictionaries first. Only if the result is inadequate in some way, rewrite it to be more like you would write it in C or Java.

Beyond that of course you need to implement the various algorithms to manipulate your trees because a quadtree is more than just some data; it is a set of rules about how to insert and delete nodes. If this is not a coursework question, then Quadtree 0.1.2 would probably be a good idea.

来源：https://stackoverflow.com/questions/2298517/are-any-of-these-quad-tree-libraries-any-good

标签

python

performance

quadtree