Is there something like 'accumulate' in mit-scheme or C++?
in [Perl]
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From: Peng Yu on 15 Jul 2010 21:27 Hi, I use the following command to OR the values in an array. I'm wondering what is the best way to do so. A function similar to 'accumulate' in mit-scheme or C++, may be helpful. But I don't find it in perl. my @array=(0,0,1); my $result=0; map { $result = $result || $_} @array; print $result, "\n"; Regards, Peng
From: Tad McClellan on 15 Jul 2010 21:35 Peng Yu <pengyu.ut(a)gmail.com> wrote: > Hi, > > I use the following command to OR the values in an array. I'm > wondering what is the best way to do so. A function similar to > 'accumulate' in mit-scheme or C++, may be helpful. But I don't find it > in perl. > > my @array=(0,0,1); > my $result=0; > map { $result = $result || $_} @array; $result ||= $_ for @array; # map in void context is silliness anyway... > print $result, "\n"; see the "Assignment Operators" section in perldoc perlop -- Tad McClellan email: perl -le "print scalar reverse qq/moc.liamg\100cm.j.dat/" The above message is a Usenet post. I don't recall having given anyone permission to use it on a Web site.
From: Ben Morrow on 15 Jul 2010 22:12 Quoth Peng Yu <pengyu.ut(a)gmail.com>: > Hi, > > I use the following command to OR the values in an array. I'm > wondering what is the best way to do so. A function similar to > 'accumulate' in mit-scheme or C++, may be helpful. But I don't find it > in perl. > > my @array=(0,0,1); > my $result=0; > map { $result = $result || $_} @array; > print $result, "\n"; The usual term for this operation is 'reduce'; you can find it in List::Util. Note that you need to explicitly provide an initial value: use List::Util qw/reduce/; my $result = reduce { $a || $b } 0, @array; In this case you could also use 'first': use List::Util qw/first/; my $result = first { $_ } 0, @array; Ben
From: Peng Yu on 16 Jul 2010 01:07 On Jul 15, 9:12 pm, Ben Morrow <b...(a)morrow.me.uk> wrote: > Quoth Peng Yu <pengyu...(a)gmail.com>: > > > Hi, > > > I use the following command to OR the values in an array. I'm > > wondering what is the best way to do so. A function similar to > > 'accumulate' in mit-scheme or C++, may be helpful. But I don't find it > > in perl. > > > my @array=(0,0,1); > > my $result=0; > > map { $result = $result || $_} @array; > > print $result, "\n"; > > The usual term for this operation is 'reduce'; you can find it in > List::Util. Note that you need to explicitly provide an initial value: > > use List::Util qw/reduce/; > > my $result = reduce { $a || $b } 0, @array; > > In this case you could also use 'first': > > use List::Util qw/first/; > > my $result = first { $_ } 0, @array; #!/usr/bin/env perl use strict; use warnings; use List::Util; my @array=1..10; my $result=List::Util::reduce { $a + $b } @array; print $result, "\n"; ########## I got the following warnings for the above problem. But the code from the manual works. I'm wondering what is wrong in the above code? Name "main::b" used only once: possible typo at ./main.pl line 8. Name "main::a" used only once: possible typo at ./main.pl line 8. my $result = List::Util::reduce { $a > $b ? $a : $b } 1..10;#this works
From: David Bouman on 16 Jul 2010 06:00
On Jul 16, 3:27 am, Peng Yu <pengyu...(a)gmail.com> wrote: > I use the following command to OR the values in an array. I'm > wondering what is the best way to do so. A function similar to > 'accumulate' in mit-scheme or C++, may be helpful. But I don't find it > in perl. What about using a grep in scalar context? -- David. |