Re: [Numpy-discussion] array from list of lists

[Erin S. <eri...@gm...>]

On 11/13/06, Charles R Harris <cha...@gm...> wrote:
>
>
> On 11/12/06, Erin Sheldon <eri...@gm...> wrote:
> > Hi all -
> >
> > Thanks to everyone for the suggestions.
> > I think map(tuple, list) is probably the most compact,
> > but the list comprehension also works well.
> >
> > Because map() is proably going to disappear someday, I'll
> > stick with the list comprehension.
> >   array( [tuple(row) for row in result], dtype=dtype)
> >
> > That said, is there some compelling reason that the array
> > function doesn't support this operation?
>
> My understanding is that the array needs to be allocated up front. Since the
> list comprehension is iterative it is impossible to know how big the result
> is going to be.

Isn't it the same with a list of tuples?  But you can send that directly to the
array constructor.  I don't see the fundamental difference, except that the
code might be simpler to write.

>
> BTW, it might be possible to use fromfile('name', dtype=dtype) to do what
> you want if the data is stored by rows in a file.

I'm reading from a database.
Erin