[Tutor] Sorting lists both ways at once and programmatically loading a variable.

[Dave Angel]

On 07/28/2011 07:05 PM, Prasad, Ramit wrote:
> I have 2 questions.
>
> 1. Is there a way to do a reverse and a normal sort at the same time?
> I have a list of tuples (there are more than 2 elements in the tuples but I only want to sort by the first two). I want to sort in reverse for the first element (int) and in order for the second element (string).
>
> Example: [ (1,3) (5, 2), (5, 1), (1, 1) ].
> The output should be:[ (5,1), (5,2), (1,1), (1,3) ]
> I can create a hack for this by sorting both values in order but it is a hack and not a "Good" solution (untested):
>>>> sorted( lst, key=lambda x: (9999999999-x[0],x[1]) )
First point.  Nothing wrong with your solution, but you can leave out 
the 999999 part.  Just use -x[0]
Another option.  Do two sorts, first on the secondary key, then on the 
primary (reversed).  Since Python's sort is stable,
     it'll do the right thing.

>
> 2. How would you programmatically get a variable when there is no class involved? If I was in a class I could do something like
>>>> programmatically_determined_variable = getattr( self, var_basename + str(number) )
> How would I do this from a module function or directly in the module? And is the solution "safe"?
>
> Ramit
>
globals() is a dictionary of all the global variables, so you can do the 
same getaddr() technique.

DaveA

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DaveA