recursive function

[Hendrik van Rooyen]

"cesco" <fd.calabrese at gmail.com> wrote:

> 
> Neil Cerutti wrote:
> > On 2007-01-08, cesco <fd.calabrese at gmail.com> wrote:
> > > Hi,
> > >
> > > I have a dictionary of lists of tuples like in the following example:
> > > dict = {1: [(3, 4), (5, 8)],
> > >         2: [(5, 4), (21, 3), (19, 2)],
> > >         3: [(16, 1), (0, 2), (1, 2), (3, 4)]]
> > >
> > > In this case I have three lists inside the dict but this number
> > > is known only at runtime. I have to write a function that
> > > considers all the possible combinations of tuples belonging to
> > > the different lists and return a list of tuples of tuples for
> > > which the sum of the first element of the most inner tuple is
> > > equal to N.
> > >
> > > For example, assuming N = 24, in this case it should return:
> > > [((3, 4), (5, 4), (16, 1)), ((3, 4), (21, 3), (0, 2)), ((5, 8), (19,
> > > 2), (0, 2))]
> >
> > What do you mean by "most inner tuple"?
> >
> > > A simple list comprehension would be enough if only I knew the
> > > number of keys/lists beforehand
> >
> > len(dict.keys()).
> 
> What I mean is that the number of keys/lists is not known until runtime
> and it changes randomly from time to time which means I would have to
> write every time a different list comprehension (or a different number
> of nested loops) to accomplish the same thing.
> In the example the result of the search should be a list containing
> three tuples each of which contains again three tuple (the most inner
> tuples). If you consider the first element of each tuple the sum is 24
> (like in 3+5+16, or 3+21+0 or 5+19+0).
> 
> Any other help will be appreciated


Is there any reliable structure in the data? 
- for instance in your example, the first list
has two tuples, the second one three, and the 
third one four - Is this a pattern?

- Hendrik