[Tutor] pickle.dump yielding awkward output
s.charonis at gmail.com
Mon Feb 4 12:12:22 CET 2013
Thank you Alan, Steven,
I don't care about the characters from the pickle operation per se, I just
want the list to be stored in its native format.
What I am trying to do is basically the Unix shell equivalent of: "Unix
command" > newfile.txt
I am trying to store the list that I get from my code in a separate file,
in human-readable format.
On Mon, Feb 4, 2013 at 1:03 AM, Alan Gauld <alan.gauld at btinternet.com>wrote:
> On 03/02/13 19:26, Spyros Charonis wrote:
>> I am experiencing a strange result with the pickle module when using it
>> to write certain results to a separate file.
> The only strangec results using pickle would be if the uinpickle failed to
> bring back that which was pickled.
> Pickle is a storage format not a display format.
> In short, I have a program that reads a file, finds lines which satisfy
>> some criteria, and extracts those lines, storing them in a list.
> Extracting them with pickle I hope? That's the only thing that should be
> used to unpickle a pickled file.
> The list of extracted lines looks like this:
>> ATOM 1 N GLN A 1 29.872 13.384 54.754 1.00 60.40
>> The output stored from the call to the pickle.dump method, however,
>> looks like this:
>> S'ATOM 1 N GLN A 1 29.872 13.384 54.754 1.00 60.40
>> N \r\n'
> Yep, I'm sure pickle can make sense of it.
> Does anyone know why the strings lp0, S', aS' are showing up?
> Because that's what pickle puts in there to help it unpickle it later.
> Why do you care? You shouldn't be looking at it (unless you want to
> understand how pickle works).
> pickle, as the name suggests, is intended for storing python objects
> for later use. This is often called object persistence in programming
> parlance. It is not designed for anything else.
> If you want cleanly formatted data in a file that you can read in a text
> editor or similar you need to do the formatting yourself or use another
> recognised format such as CSV or configparser (aka ini file).
> Alan G
> Author of the Learn to Program web site
> Tutor maillist - Tutor at python.org
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