Sorting a List of Lists

Larry Bates larry.bates at websafe.com
Wed Jan 31 01:32:02 CET 2007


apotheos at gmail.com wrote:
> I can't seem to get this nailed down and I thought I'd toss it out 
> there as, by gosh, its got to be something simple I'm missing.
> 
> I have two different database tables of events that use different 
> schemas. I am using python to collate these records for display. I do 
> this by creating a list of lists that look roughly like this:
> 
> events = [['Event URL as String', 'Event Title as String ', Event Date 
> as Datetime], ...]
> 
> I then thought I'd just go events.sort(lambda x,y: x[2]<y[2]) and call 
> it a day. That didn't work. But then lamda functions like to be very 
> simple, maybe object subscripts aren't allowed (even though I didn't 
> get an error). So I wrote a comparison function that looks much as you 
> would expect:
> 
> def date_compare(list1, 
> list2):
>     x = list1[2]
>     y = list2[2]
>     if 
> x>y:
>         return 
> 1
>     elif 
> x==y:
>         return 
> 0
>     else: # 
> x<y
>         return -1
> 
> But as before sorting with this function returns None.
> 
> What have I overlooked?
> 
Sort doesn't return a list, it sorts in place.  None is
the result code (if you will) of the sort completion.

-Larry



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