[Tutor] print as columns

[Michael P. Reilly]

Mike Serpa wrote
> > 1) you can find the longest in a list of lists by using the
> > reduce function which keeps applying the function to 
> > successive pairs of elements from a list:
> > 
> > n=len(reduce(lambda a,b:max(a,b),l))
> >   ---        ------------------- -
> >    ^            ^                ^->the list of lists (called Lists
> > in
> > your program)
> >    |            |
> >    |            |_ the function which returns the longer of two lists
> >    |
> >    |_ when the reduce is done we will know the longest list, len
> > gives the
> > length of it
> > 
> > Example:
> > 
> > a=[1,2,3,4]
> > b=[5,6,7]
> > c=[8,9,10,11,12]
> > 
> > n=len( reduce( lambda a,b:max(a,b), [a,b,c] ))
> > 
> > n is 5
> 
> Couldn't we shorten this to:
> n=len(max(lists))   
> 
> It seems that everything I figure out how to do is already in a module
> somewhere.  Question for expert Python coders (or any lang.) Do you
> ever  get to the stage where you don't have to constantly look things
> up in the lang docs?

Actually, none of these work.  The max of a list of lists is to find out
which list is greater, by component, not the longer.

>>> a = [1, 2, 3]
>>> b = [3, 4, 5, 6]
>>> max(a, b)
[3, 4, 5, 6]
>>> c = [7, 8, 9]
>>> max(b, c)
[7, 8, 9]

You probably want to use: reduce(max, map(len, seq_o_lists))

>>> reduce(max, map(len, (a, b, c)))
4

About the only thing I look to the docs for now are some of modules I
use less frequently, or when trying to verify something for the list.

  -Arcege

-- 
+----------------------------------+-----------------------------------+
| Michael P. Reilly                | arcege@speakeasy.net              |