Hi Dave,
Dave Tang wrote:
On Thu, 30 Oct 2008 16:04:31 +1000, Dave Tang <[EMAIL PROTECTED]>
wrote:
I have written the following code but I wish I could think of a much
better way of achieving my output. Any tips and suggestions will be
greatly appreciated! Thanks in advance.
Oops I mean (I wrote the code in my email) and sorry for the double post.
my $prev = 'NULL';
my $first = '';
for (my $i = 0; $i < scalar(@array); ++$i){
if ($prev eq 'NULL'){
$prev = $array[$i];
$first = $array[$i];
}
else {
if ($array[$i] == $prev + 1){
$prev = $array[$i];
}
else {
print "$first - $prev\n";
$prev = $array[$i];
$first = $array[$i];
}
}
}
print "$first - $prev\n";
__END__
You have a list of sorted numbers and you're making a single pass
through it; you are also looking at each number at most once [excluding
the starting end-point which you keep track of]. So, I can't think of
a way to make it much faster.
Your first if statement can probably be removed. You only use it once,
right? In the very beginning. You might want to set $prev and $first
to $array[0], and start the for loop from $i = 1. Or do you have NULLs
in your data?
These are co-ordinates in a genome or something? If your data file is
so large that you find that your program is too slow, you might want to
try a non-scripting language (C or C++). Another more likely problem if
your data file is too big is that the slowdown might be due to disk
accesses -- and if so, there isn't much I can think of which you can do.
Beyond these thoughts, I can't think of anything else...maybe someone
else can?
Ray
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
http://learn.perl.org/
