Load a list subset with pickle?
Robert Kern
robert.kern at gmail.com
Tue Oct 13 14:23:43 EDT 2009
On 2009-10-13 13:00 PM, Peng Yu wrote:
> I use pickle to dump a long list. But when I load it, I only want to
> load the first a few elements in the list. I am wondering if there is
> a easy way to do so? Thank you!
Not by pickling the list. However, you can concatenate pickles, so you could
just pickle each item from the list in order to the same file and only unpickle
the first few.
In [1]: import cPickle
In [2]: from cStringIO import StringIO
In [3]: very_long_list = range(10)
In [4]: f = StringIO()
In [5]: for item in very_long_list:
...: cPickle.dump(item, f)
...:
...:
In [6]: f.seek(0,0)
In [7]: cPickle.load(f)
Out[7]: 0
In [8]: cPickle.load(f)
Out[8]: 1
In [9]: cPickle.load(f)
Out[9]: 2
In [10]: cPickle.load(f)
Out[10]: 3
--
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
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