Manipulating MySQL Sets

Dave Angel davea at ieee.org
Sun Dec 13 16:35:30 EST 2009


Victor Subervi wrote:
> On Sun, Dec 13, 2009 at 12:10 PM, Carsten Haese <carsten.haese at gmail.com>wrote:
>
>   
>> Victor Subervi wrote:
>>     
>>> I need to get at the individual elements of the set (that which is
>>> between the single quotes).
>>>       
>> It's not quite clear what you mean by "get at the individual elements",
>> so I'll just show you a couple of things you can do to a set, and maybe
>> one of them comes close to what you need:
>>
>>     
>>>>> from sets import Set
>>>>> aSet = Set(['Small', 'Extra-small', 'Medium'])
>>>>>           
>> Do something for each element:
>>
>>     
>>>>> for element in aSet:
>>>>>           
>> ...     print element
>> ...
>> Small
>> Extra-small
>> Medium
>>
>> Convert the set to list:
>>
>>     
>>>>> list(aSet)
>>>>>           
>> ['Small', 'Extra-small', 'Medium']
>>
>> Test membership in the set:
>>
>>     
>>>>> 'Small' in aSet
>>>>>           
>> True
>>     
>>>>> 'Banana' in aSet
>>>>>           
>> False
>>
>> Carsten, thank you (once again ;) for your patience. I didn't know I had to
>>     
> import something.
> Thanks again,
> V
>
>   
Have you bothered to find the help file for your particular version of 
Python?  In Windows, it's a .chm file, a compiled help file, but I'm 
sure the same information is available on other distributions..  Anyway, 
sets was a module introduced in Python 2.3, and deprecated in Python 
2.6, where it's replaced by the built-in type set.  So the answer of 
whether you need to import or not depends on what version you're running.


In Python 2.5, it's  (untested)
   import sets
   data = sets.Set(mylist)

In Python 2.6 it's
    data = set(mylist)


The name datetime is both a module and a class.
    import datetime                  #import the module
    obj = datetime.datetime()   #use the class within the module you 
just imported

You can find the same information online, at least for version 2.6:
     Sometimes I'll use google to find stuff specifically on python.org, 
typing the following at the google serarch prompt::
                datetime site:python.org

     the first link in the results page is:
             http://docs.python.org/library/datetime.html
     which is the online version of the 2.6.4 help

Other useful links for the 2.6.4 documentation:
    http://docs.python.org/modindex.html         to search for modules
    http://docs.python.org/genindex.html          to search for anything

Each of these pages has a "quick search" option.  For example, I found 
the following page:
   http://docs.python.org/library/stdtypes.html#set


DaveA




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