[Chicago] Question about accessing dictionary's elements.

[Jimmy Calahorrano]

oops i mean, missleads not defeats :) 

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De:"Jimmy Calahorrano" <jcalahor at yahoo.com>
Fecha:sáb, sep 19, AM a 11:20 AM
Asunto:Re: [Chicago] Question about accessing dictionary's elements.

agreed that logic defeats the usage of dicts, maybe a binary tree search is what he is looking for.

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De:"William E. S. Clemens" <wesclemens at gmail.com>
Fecha:sáb, sep 19, AM a 10:46 AM
Asunto:Re: [Chicago] Question about accessing dictionary's elements.

I would agree that Jimmy's solution is the correct one for doing this. But I would avoid setting up your data structure in this manner. A dict is a hash table and it is be extremely fast a looking up a value by key.


You are building an array of the keys to linearly search. This operation is going to be slow and will not scale well. If you described what this data is and what your trying todo with it. I maybe able to suggest a better data structure for storing and accessing it. 





--
William Clemens
Phone: 847.485.9455
E-mail: wesclemens at gmail.com


On Sat, Sep 19, 2015 at 10:02 AM, Lewit, Douglas <d-lewit at neiu.edu> wrote:

I love it!  Thanks Jim.


On Sat, Sep 19, 2015 at 8:09 AM, Jimmy Calahorrano via Chicago <chicago at python.org> wrote:

is more elegant but not sure if is the best option:


[A[key] for key in A.keys() if key[0] == 1]



--------------------------------------------
On Sat, 9/19/15, Lewit, Douglas <d-lewit at neiu.edu> wrote:

 Subject: [Chicago] Question about accessing dictionary's elements.
 To: "The Chicago Python Users Group" <chicago at python.org>
 Date: Saturday, September 19, 2015, 7:43 AM


 Hi
 guys,
 I have a problem and not
 sure how to address it.  Let's say I have a simple
 dictionary such as.
 A = { (1, 2) : 10, (1, 3) :
 15, (1, 4) : 50, (2, 0) : 2, (2, 5) : 8, (2, 12) : 19
 }
 I would like to access any
 and all tuples whose first value is 1 or let's say 2. 
 How would I do that?
 So what I'm trying to
 go for is:
 A[(1, placeholder for any
 int value)] thus giving me all the values that correspond to
 (1, #).  Not really sure how to go about this.  Unless....
 I suppose I could do something like
 this:
 for key in
 A:     if list(key)[0]
 == 1:           
 print(A[key])  #### Or whatever I want to do with the
 number.
 Hmmm.... maybe that would
 work, but is there a more "elegant" way to do
 this?  Is there any "pattern matching" in Python
 so that I could do this:
 A[(1, #placeholder for any
 int )]
 Hey, thanks for your
 help.
 By the way, has anyone seen
 the book LEARNING PYTHON by Mark Lutz?  Wow!  Full of
 great information, but the book is HUGE!!!  I'll have
 serious back problems if I carry that thing around in my
 backpack!  There's something about small, lightweight
 books that I really prefer.  (And then there's eBooks,
 but that's a horse of a different color in my
 opinion.)
 Have a great weekend and
 I'm looking forward to some ideas on the above
 problem.  Thanks in advance.
 Best,
 Douglas
 L.

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