tabular data

[Siggy Brentrup]

poupaerte at my-deja.com writes:

> Hi
> 

[...]

> For example, say that I have the following tabular data: [(2,1,"REC02"),
> (1,3,"REC03"),(3,1,"REC01")], and I want to obtain: [(1,3,"REC03"),
> (2,1,"REC02"),(3,1,"REC01")], that is, the tabular data should be
> sorted on the first and then the second column.

> How can I have Python perform an in-place sort on a combination of
> several columns?

Simply use the list's sort() method, it does a lex sort:

Python 1.5.2 (#0, Apr  3 2000, 14:46:48)  [GCC 2.95.2 20000313 (Debian GNU/Linux)] on linux2
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> l = [(2,1,"REC02"),(1,3,"REC03"),(3,1,"REC01")]
>>> l.sort()
>>> l
[(1, 3, 'REC03'), (2, 1, 'REC02'), (3, 1, 'REC01')]
>>> l.append((1,2,'REC4'))
>>> l.sort()
>>> l
[(1, 2, 'REC4'), (1, 3, 'REC03'), (2, 1, 'REC02'), (3, 1, 'REC01')]
>>> # You may even specify a comparision function
>>> l.sort(lambda a,b: cmp((a[1],a[0]),(b[1],b[0])))
>>> l
[(2, 1, 'REC02'), (3, 1, 'REC01'), (1, 2, 'REC4'), (1, 3, 'REC03')]

> By the way, should I represent rows by tuples or by embedded lists?

See the thread "Tuples -- who needs 'en"
[Gordon McMillan]
| Lists are collections. The competing choice to a list is a
| dictionary. Tuples are toy structs; the competing choice is a class.

[...]

Regards
  Siggy

-- 
Siggy Brentrup - bsb at winnegan.de - http://www.winnegan.de/
                  bsb at north.de - http://www.north.de/~bsb/
****** ceterum censeo javascriptum esse restrictam *******