Declare list of large size

[Corrado Gioannini]

On Mon, Mar 18, 2002 at 04:43:03PM -0800, David Eppstein wrote:
> > > list = [0]*100
> > 
> > But note that this is only safe for immutable elements. You will obtain a
> > reference to the *same* object as each element.
> > 
> > This normally bites people when they try to make multi-dimensional arrays
> > ...
> > 
> > list = [[0] * 2] * 2
> > print list
> > list[0][0] = 1
> > print list
> > 
> > [[0, 0], [0, 0]]
> > [[1, 0], [1, 0]]
> > 
> > As you can see, the first element of each sub-list has been changed - this
> > is because each sub-list is in fact the same list!
> 
> I got bitten by that, once.  It took very little time to learn not to do 
> that.
> 
> So, is it considered more Pythonic to create a multidimensional array by
>     list = [[0]*100 for i in range(100)]
> and then access it by
>     ...list[i][j]...
> 
> or is it more typical to just use dictionaries?
>     list = {}
>     ...list[i,j]...

another way to build a mutable multidimensional array is simply
>>> list = eval(repr([[0] * 2] * 2))
avoiding the problem of multiple references to the same list object

do you find it too dirty, unpleasant or un-pythonic? 
(i'm really asking, it's not an ironic question ;-] )

C.
-- 
Corrado Gioannini
<gioco at nekhem.com>

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"Thought is only a flash between two long nights,
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