data structure

[Andrew Zyman]

Paul
 Thank you. In my case all "members" of a data structure are classes
(except of the id). I showed the classes to highlight the requirement to
access their methods as vs simple data types.
I think dict of lists should work.
Ideally , I hoped to access by name ( vs index), but list will do for now.
Thank you.


On 15 Jun 2017 03:07, "Paul Barry" <paul.james.barry at gmail.com> wrote:

> Hi Andrew.
>
> You start by talking about a data structure, then show code that uses
> "class".  Not everything in Python needs to be in a class.
>
> I'd look at using a simple Dictionary of lists, indexed on your ID.  A
> list can contain anything, so you can add your objects in there dynamically
> as needed.  If you need to refer to the objects by name, use a dictionary
> of dictionaries.
>
> Examples:
>
> # Dict of lists.
>
> >>> my_objects = {}
> >>> my_objects['id1'] = []
> >>> my_objects
> {'id1': []}
> >>> my_objects['id2'] = []
> >>> my_objects
> {'id1': [], 'id2': []}
> >>> my_objects['id3'] = []
> >>> my_objects
> {'id1': [], 'id2': [], 'id3': []}
> >>> my_objects['id2'].append('some data, but could be anything')
> >>> my_objects
> {'id1': [], 'id2': ['some data, but could be anything'], 'id3': []}
> >>> my_objects['id2'][0]
> 'some data, but could be anything'
>
> # Dict of dicts.
>
> >>> my_objects2 = {}
> >>> my_objects2['id1'] = {}
> >>> my_objects2['id2'] = {}
> >>> my_objects2['id3'] = {}
> >>> my_objects2
> {'id1': {}, 'id2': {}, 'id3': {}}
> >>> my_objects2['id2']['new_key'] = 'some data, but could be anything'
> >>> my_objects2
> {'id1': {}, 'id2': {'new_key': 'some data, but could be anything'}, 'id3':
> {}}
> >>> my_objects2['id2']['new_key']
> 'some data, but could be anything'
>
> I think if you concentrate on manipulating your data as opposed to trying
> to write code which manipulates it, you might be better off.
>
> I hope this helps.
>
> Regards.
>
> Paul.
>
>
>
>
>
> On 15 June 2017 at 02:36, Andrew Zyman <formisc at gmail.com> wrote:
>
>> Hello,
>>  i wonder what would be a proper data structure for something with the
>> following characteristics:
>>
>> id - number,
>> obj[a..c] - objects of various classes
>>
>> the idea is to be able to update certain fields of these objects initially
>> getting access to the record by ID
>>
>> something like this ( not working )
>>
>> ### code start
>>
>> class ClassA(object):
>>     a = ''
>>     b = ''
>>     def __init__(self):
>>         a= 'aa'
>>         b= 'ab'
>>
>> class ClassB(object):
>>     def __init__(self):
>>         self.c = 'ba'
>>         self.d = 'bb'
>>
>> def main():
>>     obja = ClassA
>>     objb = ClassB
>>
>>     sets = set(obja, objb)
>>     contracts[1] = sets
>>
>>     print('Sets ', contracts)
>>
>> # with the logic like ( not working too)
>>         if obja.a = 'aa':
>>             contracts[1].obja.a = 'ABC'
>>
>>
>>  if __name__ == '__main__':
>>     main()
>>
>>
>> ### code end
>>
>> appreciate your guidance
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>>
>
>
>
> --
> Paul Barry, t: @barrypj <https://twitter.com/barrypj> - w:
> http://paulbarry.itcarlow.ie - e: paul.barry at itcarlow.ie
> Lecturer, Computer Networking: Institute of Technology, Carlow, Ireland.
>