FLexible formatted text involving nested lists?

[davidsands]

On Oct 10, 4:36 am, RossRGK <nob... at nospam.noway> wrote:
> I'm having trouble getting my head around a solution for a situation
> where I need to flexibly format some text with a varying number of
> embedded fields.
>
> Here's a simplified description of my challenge...
>
> I have a list of lists called bigList:
>
> bigList = [ little, small, tiny]
>
> The sub-lists have varying sizes.  I won't know how many items they have
> but it will be between 0 and 3
>
> So perhaps little = [3, 2, 7]
> small = [6,4]
> tiny = [2]
>
> The values in those sub lists correspond to formatted print strings. The
> formatting strings will change over time and they are in a list called
> "fmts" where
>
> fmts = [fmtA, fmtB, fmtC]   where
>
> fmtA = 'oats %0d kilos over %0d days with %0d workers'
> fmtB = 'barley %0d lbs for %0d hours'
> fmtC = 'apples %0d baskets'
>
> If I knew how many fields were in each 'sub-list' in bigList ahead of
> time, and it never changed I could awkwardly do this:
>
> print fmtA %(little[0], little[1], little[2])
> print fmtB %(small[0], small[1])
> print fmtC %(tiny[0])
>
> or equivalently,
>
> print fmts[0] %(bigList[0][0], bigList[0][1], bigList[0][2])
> print fmts[1] %(bigList[1][0], bigList[1][1])
> print fmts[2] %(bigList[2][0])
>
> Both approaches would yield:
> oats 3 kilos over 2 days with 7 workers
> barley 6 lbs for 4 hours
> apples 2 baskets
>
> Now my challenge: since the number of fields is unknown at design time,
> my app needs to add be able to flexibly handle this.
>
> I though maybe I could use a loop that figures things out as it goes
> along. e.g...
>
> i=0
> for fmtString in fmts
>    numbOfFields = len(fmt[i])
>    print fmtString %(bigList[i][ need "for 0 to numbOffields" worth of
> indices!] )
>
> But I don't know how to have a number of items in the print expression
> that align to the numbOfFields value!?  Is there some other approach I
> can use?
>
> I thought perhaps it would accomodate extra elements in the %(...) part
> of the formatted print expression which would be ignored, but that
> doesn't work.
>
> Maybe I have to break my fmts up and do a field at a time?  Any thoughts
> are appreciated   :)
>
> -Ross.

The tuple() type-conversion function will do what you need:

   print fmts[0] % tuple(bigList[0])
   print fmts[1] % tuple(bigList[1])
   print fmts[2] % tuple(bigList[2])