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Re: Storing a big amount of path names

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Tim Chase wrote:

> On 2016-02-12 00:31, Paulo da Silva wrote:
>> What is the best (shortest memory usage) way to store lots of
>> pathnames in memory where:
>> 
>> 1. Path names are pathname=(dirname,filename)
>> 2. There many different dirnames but much less than pathnames
>> 3. dirnames have in general many chars
>> 
>> The idea is to share the common dirnames.
>
> Well, you can create a dict that has dirname->list(filenames) which
> will reduce the dirname to a single instance.  You could store that
> dict in the class, shared by all of the instances, though that starts
> to pick up a code-smell.
>
> But unless you're talking about an obscenely large number of
> dirnames & filenames, or a severely resource-limited machine, just
> use the default built-ins.  If you start to push the boundaries of
> system resources, then I'd try the "anydbm" module or use the
> "shelve" module to marshal them out to disk.  Finally, you *could*
> create an actual sqlite database on disk if size really does exceed
> reasonable system specs.
>
> -tkc
>

Probably more memory efficient to make a list of lists, and just declare
that element[0] of each list is the dirname.  That way you're not
wasting memory on the unused entryies of the hashtable.

But unless the OP has both a) plus of a million entries and b) let's say
at least 20 filenames to each dirname, it's not worth doing.

Now, if you do really have a million entries, one thing that would help
with memory is setting __slots__ for MyFile rather than letting it
create an instance dictionary for each one.

-- 
Rob Gaddi, Highland Technology -- www.highlandtechnology.com

Email address domain is currently out of order.  See above to fix.

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Thread

Storing a big amount of path names Paulo da Silva <p_s_d_a_s_i_l_v_a_ns@netcabo.pt> - 2016-02-12 00:31 +0000
  Re: Storing a big amount of path names Chris Angelico <rosuav@gmail.com> - 2016-02-12 11:39 +1100
  Re: Storing a big amount of path names Ben Finney <ben+python@benfinney.id.au> - 2016-02-12 11:44 +1100
  Re: Storing a big amount of path names Tim Chase <python.list@tim.thechases.com> - 2016-02-11 19:13 -0600
    Re: Storing a big amount of path names Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2016-02-12 02:17 +0000
  Re: Storing a big amount of path names MRAB <python@mrabarnett.plus.com> - 2016-02-12 03:13 +0000
  Re: Storing a big amount of path names Chris Angelico <rosuav@gmail.com> - 2016-02-12 14:49 +1100
    Re: Storing a big amount of path names Paulo da Silva <p_s_d_a_s_i_l_v_a_ns@netcabo.pt> - 2016-02-12 04:15 +0000
      Re: Storing a big amount of path names Chris Angelico <rosuav@gmail.com> - 2016-02-12 15:23 +1100
        Re: Storing a big amount of path names Paulo da Silva <p_s_d_a_s_i_l_v_a_ns@netcabo.pt> - 2016-02-12 04:45 +0000
          Re: Storing a big amount of path names Chris Angelico <rosuav@gmail.com> - 2016-02-12 16:02 +1100
            Re: Storing a big amount of path names Paulo da Silva <p_s_d_a_s_i_l_v_a_ns@netcabo.pt> - 2016-02-12 05:49 +0000
            Re: Storing a big amount of path names Steven D'Aprano <steve@pearwood.info> - 2016-02-12 16:51 +1100
        Re: Storing a big amount of path names Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2016-02-12 17:05 +0000
          Re: Storing a big amount of path names Chris Angelico <rosuav@gmail.com> - 2016-02-13 04:18 +1100
          Re: Storing a big amount of path names Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-02-12 21:37 +0000
          Re: Storing a big amount of path names Ben Finney <ben+python@benfinney.id.au> - 2016-02-13 08:49 +1100
          Re: Storing a big amount of path names Matt Wheeler <funkyhat@gmail.com> - 2016-02-12 23:31 +0000
            Re: Storing a big amount of path names mkondrashin@gmail.com - 2016-02-13 12:19 -0800
  Re: Storing a big amount of path names srinivas devaki <mr.eightnoteight@gmail.com> - 2016-02-12 11:46 +0530

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