[SciPy-user] object_arrtype addition error

Chris Fonnesbeck fonnesbeck at gmail.com
Tue Nov 29 09:38:43 CST 2005


On 11/29/05, Chris Fonnesbeck <fonnesbeck at gmail.com> wrote:
> On 11/29/05, Chris Fonnesbeck <fonnesbeck at gmail.com> wrote:
> > On 11/28/05, Travis Oliphant <oliphant.travis at ieee.org> wrote:
> > > Chris Fonnesbeck wrote:
> > >
> > > >Under scipy_core, I have a dictionary that contains what I thought
> > > >were floating point numbers, but are actually 'object_arrtype':
> > > >
> > > >
> > > >
> > > One question is why these are object array scalars (entries in an object
> > > array), instead of floating point numbers in the first place.  Perhaps
> > > there is something going on there.
> > >
> >
> > Its just my PyMC code calculating the quantiles of the trace (the big
> > array of sampled values), and throwing those values into a dictionary:
> >
>
> I figured it out. The trace array is intitialized as:
>
> self._trace = array([None]*size)
>
> Which, of course, is of type object_arrtype. When each element is
> replaced by a proper value, the type does not change. I suppose I have
> to initialize to float values, though I liked using None's under
> numeric because if for some reason the whole array was not populated,
> I would get an error if I tried to do anything useful with the array.
>

This brings up a question, then, about how to initialize an array when
you dont know ahead of time what type it will contain. I like to
initialize a large array at the beginning and populate it, rather than
iteratively append to a growing array (that's the Pythonic way,
right?).

C.

--
Chris Fonnesbeck
Atlanta, GA



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