list subsetting

Robert Kern robert.kern at gmail.com
Wed Jan 21 23:47:56 CET 2009


culpritNr1 wrote:
> Thank you Fogelbird and Jeff.
> 
> I actually tried to find out if such function existed. I did
> 
>>>> help("count")
> no Python documentation found for 'count'
> 
> Anyway. More than counting, I am interested in list subsetting in a simple
> way. Forget about counting. Say I have a list of lists and I want to pull
> only the rows where the second "column" equals 3.14.

In [1]: list_o_lists = [[1, 3.14, 3, 4],
    ...:   [2, 3, 4, 5],
    ...:   [3, 3.14, 5, 6]]

In [2]: print [L for L in list_o_lists if L[1] == 3.14]
[[1, 3.1400000000000001, 3, 4], [3, 3.1400000000000001, 5, 6]]

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco




More information about the Python-list mailing list