Re: some combination of std::distance/std::max_element ( ? )

From:
Alberto Ganesh Barbati <AlbertoBarbati@libero.it>
Newsgroups:
comp.lang.c++.moderated
Date:
27 Apr 2006 15:04:01 -0400
Message-ID:
<dU14g.99016$A83.2310967@twister1.libero.it>
ma740988 ha scritto:

Given a sequence with n elements. For instance:
    double arr [ 6 ] = { 0., 2., 4., 5., 6., 7.}
I'll define - what I call 'test zones' . Within these test zones I'll
seach for _and_ store max values and position found.
For instance: Lets assume 2 test zones. This would equate to:
Zone 1 elements: 0., 2., 4
Zone 2 elements: 5., 6., 7

Max value - zone 1 = 4, location 2 ( element index)
Max value - zone 2 = 7, location 5 ( element index)

<snip>

At issue: I'm thinking some combination std::distance and
std::max_element would work better. Sample source on how to achieve
this greatly appreaciated.


Looks like a homework to me... ;)

---------
if(sequence1.size() >= t_zone)
{
   typedef std::deque<double>::iterator iterator;
   iterator it = sequence1.begin();
   iterator end = sequence1.end() - (t_zone - 1);
   for(; it < end; it += t_zone)
   {
     iterator max_it = std::max_element(it, it + t_zone);
     mMap[max_it - sequence1.begin()] = *max_it;
   }
}
---------

You don't need std::distance() because deque provides random iterators
so using binary "-" is just as good. If you want to stick to it, replace

   max_it - sequence1.begin()

with

   std::distance(sequence1.begin(), max_it)

Notice that if the sequence size is not a multiple of t_zone, the last
"partial" zone is not considered at all, as it was in your original
code.

HTH,

Ganesh

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