[Numpy-discussion] Pickling and initializing

[Robert Kern]

On Mon, Mar 3, 2008 at 5:29 PM, Dinesh B Vadhia
<dineshbvadhia at hotmail.com> wrote:
>
>
> When you pickle a numpy/scipy matrix does it have to be initialized by
> another program?  For example:
>
> Program One:
>     A = scipy.asmatrix(scipy.empty((i, i)), dtype=int)        # initialize
> matrix A
>     <do something with A>
>     pickle.dump(A)
>
> Program Two:
>     pickle.load(A)
>
>
> ... in Program Two, do we need the statement:
>
>     A = scipy.asmatrix(scipy.empty((i, i)), dtype=int)        # initialize
> matrix A
>
> before the pickle.load(A)?

No. Neither pickle.load() nor pickle.dump() work like that. The
signature of pickle.dump() is

  pickle.dump(f, obj)

and the signature of pickle.load() is

  obj = pickle.load(f)

where `f` is an open file object. There is no need to "pre-declare"
`obj` before loading it.

> If not, why not and doesn't this make documentation difficult?

Not particularly, no.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco