On Wed, 16 Nov 2005 13:58:45 +0100, Peter Kleiweg wrote:
>
> This does not what I want it to do:
>
> >>> a = [[]] * 6
> >>> a[3].append('X')
> >>> a
> [['X'], ['X'], ['X'], ['X'], ['X'], ['X']]
>
> This does what I want:
>
> >>> b = [[] for _ in range(6)]
> >>> b[3].app
Peter Kleiweg wrote:
>> http://www.python.org/doc/faq/programming.html#how-do-i-create-a-multidimensional-list
>
> In other words: no there isn't.
For people who actually knows Python, a list comprehension is clear and
obviously correct.
For people who actually knows Python, your first solution
Peter Kleiweg wrote:
> This does not what I want it to do:
>
> >>> a = [[]] * 6
> >>> a[3].append('X')
> >>> a
> [['X'], ['X'], ['X'], ['X'], ['X'], ['X']]
>
> This does what I want:
>
> >>> b = [[] for _ in range(6)]
> >>> b[3].append('X')
> >>> b
> [[], [], [],
Hello,
>>> b = [[] for _ in xrange(6)] # <- note the xrange!
>>> b[3].append('X')
>>> b
[[], [], [], ['X'], [], []]
This syntax might be less hairy but could be better when you use large table.
You can hide this syntax by making a function:
def buildMatrix(nbRows):
return [[] for _ in xrange
Fredrik Lundh schreef op de 16e dag van de slachtmaand van het jaar 2005:
> Peter Kleiweg wrote:
>
> > This does not what I want it to do:
> >
> >>>> a = [[]] * 6
> >>>> a[3].append('X')
> >>>> a
> >[['X'], ['X'], ['X'], ['X'], ['X'], ['X']]
> >
> > This does what I want:
> >
> >
Peter Kleiweg wrote:
> This does not what I want it to do:
>
>>>> a = [[]] * 6
>>>> a[3].append('X')
>>>> a
>[['X'], ['X'], ['X'], ['X'], ['X'], ['X']]
>
> This does what I want:
>
>>>> b = [[] for _ in range(6)]
>>>> b[3].append('X')
>>>> b
>[[], [], [], ['X'], [],
This does not what I want it to do:
>>> a = [[]] * 6
>>> a[3].append('X')
>>> a
[['X'], ['X'], ['X'], ['X'], ['X'], ['X']]
This does what I want:
>>> b = [[] for _ in range(6)]
>>> b[3].append('X')
>>> b
[[], [], [], ['X'], [], []]
The first is clear and wrong.
