unbalanced tree iteration issue

Fri Jan 14 08:29:34 EST 2011

14.01.2011, 14:15, "Alex Boyko" <alex.kyrish at gmail.com>:
> Dear All!
>> I have deal with large unbalanced trees and I have to implement post-order tree traversal. My first attempt is shown below ("Node" and "Tree" classes) and based on recursive generators approach.
>> class Node():
>     def __init__(self,value):
>         self.childs = []
>         self.value = value
>> class Tree():
>>     def __init__(self, root):
>         self.root = root
>         self.numberCells = 1
>>     def add(self, node, child):
>         node.childs.append(child)
>         self.numberCells+=1
>>     def __iter__(self):
>         return self.postorder(self.root)
>>     def postorder(self, node):
>         if node:
>             for child in node.childs:
>                 for n in self.postorder(child):
>                     yield n
>             yield node
>> It works fine for small test trees. But, my tree has approximately 300000 nodes, and shown post order traversal with generators takes 80 sec against 1 sec with simple recursive routine:
>> def recursiveFromTop(node):
>     for child in node.childs:
>         recursiveFromTop(child)
>         ## here I can do some computations with current node's data
>> So, I'd like to know how should I implement (if it's possible of course) __iter__ for my tree class based on recursion without generators? Please, can You show me the ways?
> because I'm very passionate in idea iterate through my tree with simple:
>> for node in tree:
>    do something with node
>> Thanks in Advance!
> Best Regards!
> Alex
>> --
> http://mail.python.org/mailman/listinfo/python-list

Forgot to make new-style object)
class Node(object):
The results for new-style objects are:
$ python postorder.py 
building tree...done
0:00:26.180799
doing generator post_order...done
0:00:00.000017
doing non-generator post_order...done
0:00:01.117986
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