[Chicago] Question about accessing dictionary's elements.

Sat Sep 19 20:58:08 CEST 2015

Yea what time on monday is good for you. can you email me off list?
zitterbewegung at gmail.com

On Sat, Sep 19, 2015 at 1:56 PM Lewit, Douglas <d-lewit at neiu.edu> wrote:

> You have any time on Monday?  I really gotta get going.  If I sit in front
> of this laptop any longer, I'm going to go completely crazy!  I spent all
> morning working on the code for the KNN algorithm, and I'm still not really
> done with it!  (But pretty close I think.... I hope! )
>
> On Sat, Sep 19, 2015 at 1:54 PM, Joshua Herman <zitterbewegung at gmail.com>
> wrote:
>
>> umm i can do skype
>>
>>
>> On Sat, Sep 19, 2015 at 1:46 PM Lewit, Douglas <d-lewit at neiu.edu> wrote:
>>
>>> Hey Joshua!  I would LOVE to, but I have classes on Wednesday and
>>> Thursday evenings.  So.... ???
>>>
>>> On Sat, Sep 19, 2015 at 1:30 PM, Joshua Herman <zitterbewegung at gmail.com
>>> > wrote:
>>>
>>>> Hey I'm doing machine learning too why don't you come to one of the
>>>> python meet ups in Chicago
>>>>
>>>> On Sat, Sep 19, 2015 at 12:56 PM Lewit, Douglas <d-lewit at neiu.edu>
>>>> wrote:
>>>>
>>>>> Hi William,
>>>>>
>>>>> I'm doing a KNN program (K-Nearest-Neighbors).  I'm attaching what
>>>>> I've done so far.  It's not complete!  But I've made good progress I think.
>>>>>  (The program won't work unless you also download the .txt file that the
>>>>> program uses to read in the data.)
>>>>>
>>>>> For this problem the data has to get split into two sets: a training
>>>>> set (kind of like a control group in an experiment) and the test set (the
>>>>> experimental group or its equivalent).  I have to use the K smallest
>>>>> normalized distances to make a guess about which class the records in the
>>>>> Training Set belong to.  (There are six classes: {1, 2, 3, 5, 6, 7}.
>>>>> There's no class #4.)
>>>>>
>>>>> This problem has given me a massive headache, but I think I'm almost
>>>>> done with it.  All that's left really is to use one of the algorithms to
>>>>> make a decision about which class each Test record should be assigned to.
>>>>>
>>>>> Thanks for the feedback!
>>>>>
>>>>> Best,
>>>>>
>>>>> Douglas.
>>>>>
>>>>>
>>>>> On Sat, Sep 19, 2015 at 10:45 AM, William E. S. Clemens <
>>>>> wesclemens at gmail.com> wrote:
>>>>>
>>>>>> 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.
>>>>>>>>
>>>>>>>>  -----Inline Attachment Follows-----
>>>>>>>>
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