Re^5: Sub-setting an Array

Like this?

#!/usr/bin/perl
use strict;
use warnings;

my @array = qw/ c h e a p s l i d i n g w i n d o w /;

my $elements = @array;

for ( my $offset = 0; $offset < $elements; $offset++ ) { 
  for my $length ( 1 .. 3 ) { 
    next if $length != 3 and $offset >= 1;
        
    my @to_splice = @array;
    my @spliced = splice @to_splice, $offset, $length;
        
    print "@spliced\n";
  }
}

__END__
[download]

Output:

$ perl 1141079.pl
c
c h
c h e
h e a
e a p
a p s
p s l
s l i
l i d
i d i
d i n
i n g
n g w
g w i
w i n
i n d
n d o
d o w
o w
w
$
[download]

Note that a "sliding window" is a Thing and if you do some research you'll probably find existing tools for implementing it in your program.

The way forward always starts with a minimal test.

Comment on Re^5: Sub-setting an Array Select or Download Code

Replies are listed 'Best First'.
Re^6: Sub-setting an Array by Anonymous Monk on Sep 05, 2015 at 01:17 UTC
Interesting, I have never heard of "sliding windows" before. I do not want the final windows to have less than 3 elements so, if I look at your output, the code would have to stop after "d o w".	[reply]
Re^7: Sub-setting an Array by 1nickt (Canon) on Sep 05, 2015 at 01:27 UTC
Well, how would you say that in English? Something like "Stop if the difference between the position of the element we're on and the length of the array is smaller than the length of the window we want", right? So in Perl that might be as simple as: `last if $elements - $offset < 3;` [download] Which will stop the whole loop as soon as it's true. Add it after the `next` statement and see what happens. Edit: If you are really wanting to get a sliding subset of the array, you wouldn't want to use `splice` since as you can see it changes the original array and soon you have no elements left! But making a copy of the array each time through a loop, as I did in the example, is horribly inefficient, and the example is only designed to explain the use of `splice`, which is what the OP asked for ... The way forward always starts with a minimal test.	[reply] [d/l] [select]
Re^8: Sub-setting an Array by kgherman (Novice) on Sep 05, 2015 at 01:33 UTC
Makes perfect sense! Thanks for your feedback.	[reply]
Re^8: Sub-setting an Array (sliding window is fifo/queue...?) by Anonymous Monk on Sep 05, 2015 at 02:27 UTC
Interesting, I have never heard of "sliding windows" before.... Well, how would you say that in English? Great question Maybe a FIFO/Queue of size N? Hmm, there is a Sliding window protocol, haha	[reply]