How to generically transform a list?

Arthur Rambo arambo314 at hotmail.com
Fri Aug 27 04:41:14 CEST 2004


As simple as

theList=[['a',1,11,'aa'], ['b',2,22,'bb'],['c',3,33,'cc']]
returnList=[2,1]

newList=[[item[index] for index in returnList] for item in theList]

Python rules...

> Suppose you have a list of lists:
> 
> theList = [['a',1,11,'aa'], ['b',2,22,'bb'],['c',3,33,'cc']]
> 
> I would like to have a GENERIC way how to turn this list of list into 
> another list of list.
> - A user can choose which columns she wants
> - A user can select the order of the columns
> 
> For example:
> The user wants columns: 1,2
> The user wants it to be ordered: 2,1
> 
> A non generic approach would maybe do the following:
> 
> >>> theList = [['a',1,11,'aa'], ['b',2,22,'bb'],['c',3,33,'cc']]
> >>> new_list = [[row[2], row[1]] for row in theList]
> >>> new_list
> [[11, 1], [22, 2], [33, 3]]
> 
> I am sure there must be a rather elegant generic approach, which is 
> lurking somewhere to be realeased.
> 
> Thanks for any hint in advance,
> Marco



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