max() of a list of tuples

Erik Max Francis max at alcyone.com
Fri Jan 24 01:54:26 CET 2003


Peter Abel wrote:

> And if there's no initial value, it seems the
> reduce-function starts with the first element of l.
> (As I said l[0] <wink>)

Well, of course.  That's what reduce _does_.  It repeatedly applies a
binary function to the elements of the sequence, accumulating the
result.  Specifying the third argument -- the initial value -- is only
necessary if 1. the sequence is empty or 2. you want the initial value
to be something other than what it would normally be.

The vagueness here is, of course, because reduce works on _any_ function
that accumulates values over any types of elements, not just numeric
ones.

Specifying 

	reduce(f, S, i)

is really precisely equivalent to

	reduce(f, [i] + S),

provided of course that the sequence is compatible with being added to a
list, etc.

-- 
 Erik Max Francis / max at alcyone.com / http://www.alcyone.com/max/
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/  \ An undevout astronomer is mad.
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