[Tutor] output of dictionaries

[Karl Pflästerer]

On 10 Mai 2005, tomcloyd at bestmindhealth.com wrote:

> I'm creating a small database using a dictionary of dictionaries, and I  
> want to output it to a file. It seems that only strings can be output to  
> files, and I cannot quite figure out how to quickly and simply convert my  
> dictionary to a list of strings or whatever. Or maybe I'm going about this  
> all wrong.

> So, the most general form of my question: how can I store a dictionary  
> containing some data records stored as dictionaries - a dictionary of  
> dictionaries - in a file, so I can read it back in later and process its  
> contents?

You could use the pickle module to serialize and deserialize your data.

Here's an example (very simple):

. >>> import pickle
. >>> d
. {1: {2: 3, 3: 4}, 2: {2: 3, 3: 4}, 3: {2: 3, 3: 4}}
. >>> f = open("test.pickle", "w")
. >>> pickle.dump(d, f)
. >>> f.close()
. >>> f = open("test.pickle")
. >>> d2 = pickle.load(f)
. >>> f.close()
. >>> d2 == d
. True

Or take a look at the shelve module; it could be just what you want.


   Karl
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