improving a huge double-for cycle

Paul Hankin paul.hankin at
Thu Sep 18 22:14:50 CEST 2008

On Sep 18, 2:25 pm, Alexzive <zasaconsult... at> 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)

Using only a little extra storage to compute IN (but O(N log N)
time complexity):

import itertools

SN = [k for k, v in itertools.groupby(IN) if len(list(v)) > 1]

Paul Hankin

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