python bisect questions

ankitks.mital at gmail.com ankitks.mital at gmail.com
Fri Apr 4 01:29:07 CEST 2008


On Apr 3, 5:43 pm, John Machin <sjmac... at lexicon.net> wrote:
> On Apr 4, 9:21 am, ankitks.mi... at gmail.com wrote:
>
>
>
>
>
> > On Apr 3, 4:24 pm, "Terry Reedy" <tjre... at udel.edu> wrote:
>
> > > <ankitks.mi... at gmail.com> wrote in message
>
> > >news:6bb6927b-f553-40db-a142-2ce86b9e819f at q27g2000prf.googlegroups.com...
> > > |I am week on functional programming, and having hard time
> > > | understanding this:
> > > |
> > > | class myPriorityQueue:
> > > |      def __init__(self, f=lamda x:x):
> > > |              self.A = []
> > > |              self.f = f
> > > |
> > > |      def append(self, item)
> > > |              bisect.insort(self.A, (self.f(item), item))
> > > |    ............
> > > |
> > > | now I know we are inserting items(user defined type objects) in list A
> > > | base on sorting order provided by function A.
> > > | but what I don't understand is bisect command
> > > | what does bisect.insort(self.A, (self.f(item), item)) doing
>
> > here is doc
> > insort_right(a, x[, lo[, hi]])
>
> >     Insert item x in list a, and keep it sorted assuming a is sorted.
>
> >     If x is already in a, insert it to the right of the rightmost x.
>
> >     Optional args lo (default 0) and hi (default len(a)) bound the
> >     slice of a to be searched.
>
> > but I am still confuse. self.A is my list a. and item is x that
> > I am trying to insert.
> > So it needs to be of type item not (self.f(item), item)
> > It doesn't say anything pass sorting function self.f(item).
>
> That's correct. You are passing a tuple of (sort_key, actual_data).
>
> Example use case: caseless sortorder but you want to retrieve the
> original data. f is lambda x: x.upper() or similar. Your data is
> 'foo', 'Bar', 'zOt'. Calls to your_queue.append will result in the
> following 2nd args for bisect.insort:
> ('FOO', 'foo')
> ('BAR', 'Bar')
> ('ZOT', 'zOt')

Thanks John and Terry,
Wow! great way to keep original values with transformation.
Thanks for explaining.

>
> Consider executing the code with a couple of print statements in it so
> that you can see what is happening.- Hide quoted text -
>
> - Show quoted text -




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