Question

I think its called a slice…

basically I have a list of lists:

[['fmt/10', 3L, 5L, Decimal('9500')], 
['fmt/353', 1L, 1L, Decimal('500')], 
['fmt/7', 3L, 5L, Decimal('9500')], 
['fmt/8', 3L, 5L, Decimal('9500')], 
['fmt/9', 3L, 5L, Decimal('9500')]]

and I want to pull out 4 new lists, all at position [0], [1], [2] and [3].

so if would look like:

A = ['fmt/10', 'fmt/353','fmt/7','fmt/8','fmt/9']
B = [3,1,3,3,3] 
C = [5,1,5,5,5]
D = [9500,500,9500,9500,9500]

Whats the simplest way to achieve this?
From reading around I think I want to use ‘zip’ but I’m not sure how that works.

Answer 1

L = [['fmt/10', 3L, 5L, Decimal('9500')], 
     ['fmt/353', 1L, 1L, Decimal('500')], 
     ['fmt/7', 3L, 5L, Decimal('9500')], 
     ['fmt/8', 3L, 5L, Decimal('9500')], 
     ['fmt/9', 3L, 5L, Decimal('9500')]]

zip(*L) (the asterisk is being used to unpack the list) will give:

[('fmt/10', 'fmt/353', 'fmt/7', 'fmt/8', 'fmt/9'),
 (3L, 1L, 3L, 3L, 3L),
 (5L, 1L, 5L, 5L, 5L),
 (Decimal('9500'), Decimal('500'), Decimal('9500'), Decimal('9500'), Decimal('9500'))]

and you may use the destructuring assignment:

A, B, C, D = zip(*L)