The code i'm using is the following:
for line in lista:
if sum(line == 0) > 0:
lista.remove(line)
The problem is that the loop stops at the first line with zeros and
it doesn't remove the other lines with zeros (at least if I do not
re-run the loop). Probably I do not understand how the loop works.
The loop will assign the first element of lista to line, then the
second, then the third, and so on.
The problem is that, if you remove an element everything after it
shifts up one place. Say you are looking at the first element and
remove it, what was the second element now becomes the first element,
but the next time round the loop you will look at the new second
element and the one that was originally second (and is now first) will
be skipped.
The solution is never to work on the list you are modifying. Just make
a copy of the list and iterate over the copy, that means you can
safely modify the original. To copy a list, use the 'list' builtin.
for line in list(lista):
if condition:
lista.remove(line)
Alternatively turn your brain around and instead of deleting specific
elements from the list just build a new list with the elements you
want to keep. In this case you could do that using a list
comprehension:
lista = [ line for line in lista if not condition ]
(Obviously in both these cases replace condition with the correct
expression, which as Gerhard pointed out may not be the condition in
your original posting.)
The list comprehension rebinds the lista variable, whereas your
original attempt was modifying the list inplace. This might be
significant if there are other references to the same list elsewhere
in your code. If it does matter, then you can still use a list
comprehension to mutate the original list:
lista[:] = [ line for line in lista if not condition ]
Unlike the original 'for' loop, this works by building a complete
replacement list then mutating the original list in one go.
--
Duncan Booth
(e-mail address removed) int month(char
*p){return(124864/((p[0]+p[1]-p[2]&0x1f)+1)%12)["\5\x8\3""\6\7\xb\1\x
9\xa\2\0\4"];} // Who said my code was obscure?--
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