[Tutor] Response to responses about list of lists: a meta exercise in mailinglist recursion

[Siren Saren]

I'm not sure if there's a way to submit responses 'live' or
whether it's better to respond to subthreads at once or together, so I'll err
on the side of discretion and just send one response.  Thanks to each of you who tried to help me.  I've responded individually below. 

 

To summarize the discussion so far:


I wondered if there was a decent way to sort a list that
contained two lists, where each could be distinguished based on the list's sequence and
the elements' data characteristics.  As a subsidiary
question, I wondered if there was a data structure I should aspire to put the
data into once I had it sorted.


In response to the first question: the consensus seems to be
that there is no good way to sort a non-alternating one-to-many list like this, so my strategy of deriving
the index numbers of every item, as awkward as it appears, may actually be the
best approach. 

 

In response to the second: a pickle, a dictionary, a
database, and a tuple with a sublist were all proposed.    The choice seems somewhat arbitrary, but on
the bright side, I suppose that also confirms that I have a lot of flexibility
in what I choose.  



Specific responses:


Steven,

I apologize for using 'reply,' I've never used a mailing
list before and didn't understand what would happen.  Is there some online forum where I could post
a message directly rather than mailing it in? 
I see that other people are somehow responding to my message from the
more real-time updates I can get on activestate, but I don't know how they are
doing it since I haven't received the mailing yet that would include my message
and its responses.  

If my list had a million books in it and 10 million page
numbers, would the approach I've outlined in my initial post be the best for
sorting them?  Like David and Eric you've
given me some good input on a data structure to use.  If I understand you right, you'd advocate
using a tuple of the books, bookmarks, where the bookmarks themselves are
sublists.  


David, Yes, I agree it would 
be much better to store the data in a different manner.  The problem is that I'm not the creator of
the data.  Maybe you realize that and are
just suggesting the database structure rather than a dictionary or a pickle,
once I get my sorting accomplished?  If
the book example is confusing how about this. 
Say you discovered a bunch of data in a secret code document.  You know the sequence of the data relates the
elements to each other.  You also know
there are just two elements and that the sequence is a straightforward function
of say, integers to letters.  So the data
you've discovered looks like:


A 2 3 B 4 7 5 9 1 C 3 2 1 0 0 4 D 3 3 32 44 ...


Once I've sorted the data, I am curious how to best store it
(and why), and your answer does pertain to that-- use sql-- but I am also
curious if there's a less arcane approach than the one I'm using to try to do
the initial sorting.  Any thoughts, given
that I can't fix the way the data arrives? 
Thanks for the database idea regardless.


Eric, I appreciate your input though I'm hard-pressed to
find its applicability.  It may be useful
as a way to store my data for this or any number of other programs though, and
that was a helpful article about the pickling process.  I don't know if pickle has any built-in
methods for relating data to other data. 
I'd imagine that if I were designing the data input process, rather than
just taking data that exists and trying to process it, I'd probably go with a
database for a situation like this.  Then
I'd have a more explicit system for referring each value to other values
through records, rather than having to infer them as I'm doing.  Regardless, I'm often in the same position of
trying to be helpful without knowing how, and I sincerely do appreciate the
attempt.  It creates a general atmosphere
of friendliness, which is so much better than being told I'm an idiot :)!


Lingering Questions: 

Anyone have a rationale for choosing
one of the data structures proposed? 
Anyone have a better way to do the sorting than the process I outlined
in my first post (a. identify the elements. b. make a list of one of  the element groups. c. get the index numbers
of that group in the broader list.  d.
list the other elements as indexes falling between the first group's indexes.  e. reorganize the data into a more logical
form)


Thanks again to everyone who responded!


Soren


      
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