View Full Version : [python] modify a list

10 October 2011, 11:45 AM
Hi there ,

i would like to reorder a list by filtering it , but dont find how.

i got a list : [curve1, curve2, curve3, subCurve1, subCurve2] and would like to get : [curve1, subCurve1, curve2, subcurve2, curve3] .

is it something that is possible?


10 October 2011, 12:37 PM
Not very elegant way, but should work.

newList = []
for i in curveList:
if i.startswith("curve"):
subname = i.replace("curve", "subCurve")
if subname in curveList:

10 October 2011, 01:55 PM
Thanks you !

why did you say" it s not a elegant way" to do that?

10 October 2011, 02:13 PM
your question is not quite explicit enough.

do you simply want to "group" a curve# with a corresponding subCurve#..? or do you mean you want to SORT the list based on the number in the name?
what happens if the names are NOT curve#and subCurve#..?

Haggi's solution only works for the former, and doesn't actually sort them into order (which may not be an issue, you didn't specify). That's why he says it's not very elegant, it only works for a very specific situation.

For the latter method, if you wanted to sort your list based on an arbitrary index somewhere in it's name, python sort is customizable so you can sort based on any part of an item:

li = ['curve3', 'curve1', 'curve2', 'subCurve1', 'subCurve4', 'curve6']
import re
li.sort(key=lambda x:'[0-9]+',x).group())
print lithe sort key is a little complicated due to the lambda and the regular expressions, but show's what you can do with very little.

10 October 2011, 02:30 PM
yep , i realised it was not explicit enough.

The idea is i create some main Controllers [ctrlCrv1,ctrlCrv2,ctrlCrv3.....]

Then , i have some secondary controllers whixh can be : [subCtrl1, subCtrl2,subCtrl3 ....]
or : [subCtrl1_1, subCtrl1_2, subCtrl2_1, subCtrl2_2....]

What i want to do is to sort the list of all the controllers in this way :
[ctrlCrv1, subCtrl1_1, subCtrl1_2, ctrlCrv2, subCtrl2_1, subCtrl2_2..... ]

Your solution is exactly what i need .
i just learn something very useful.

Thanks to both of you

10 October 2011, 10:07 PM
Thats what I call more elegant :)
I'm not very good with lambdas, but I like the compact form.

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10 October 2011, 10:07 PM
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