Re: improving a huge double-for cycle

[Tino Wildenhain]

Tino Wildenhain wrote:

Hi,

Alexzive wrote:

Hello there :) ,

I am a python newbie and need to run following code for a task in an
external simulation programm called "Abaqus" which makes use of python
to access the mesh (ensamble of nodes with xy coordinates) of a
certain geometrical model.

[IN is the starting input containing the nodes to be check, there are
some double nodes with the same x and y coordinates which need to be
removed. SN is the output containing such double nodes]

Code: Select all
    for i in range(len(IN)): #scan all elements of the list IN
      for j in range(len(IN)):
        if i <> j:
         if IN[i].coordinates[0] == IN[j].coordinates[0]:
           if IN[i].coordinates[1] == IN[j].coordinates[1]:
              SN.append(IN[i].label)

data=dict()
for item in IN: # (what a name! ;)
    data.setdefault(item.coordinates,[]).append(item)
    # provided coordinates is a tuple

dupes=[items for items in data.values() if len(items)>1]

should give you a resulting list of lists of elements in IN
which occur more then once per coordinates.
You can then decide which ones to remove or whatever.

If you want to have the output only containing nodes to remove,
the following would work:

dupes=[]
for items in data.values():
    dupes.extend(items[1:])

I did a small test - I don't know if it reflects
the actual problem good enough but it seems it
all runs below 1 sec each so this would be very
fast compared to 15h:

>>> import random
>>> class Node(object):
...     def __init__(self,x,y):
...             self.coordinates=(x,y)



>>> data=dict()
>>> for item in IN: data.setdefault(item.coordinates,[]).append(item)
...

>>> dupes=[items for items in data.values() if len(items)>1]
>>> len(dupes)
10190
>>>

Cheers
Tino

>>> IN=[Node(random.randint(0,100),random.randint(0,100)) for i in xrange(100000)]

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