Iterate trough a series of folders

BlueStarry has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Iterate trough a series of folders by kennethk (Abbot) on Apr 04, 2016 at 17:42 UTC
The problem you are having is that readdir returns the directory contents without path information. You probably want to change that to `my @dirs = grep {-d "$dir/$_"} readdir($gdh);` [download] or even better `my @dirs = grep {/[^.]/ and -d "$dir/$_"} readdir($gdh);` [download] and `opendir (my $tdh, "$dir/$tumordirs") or die "Unable to open subdir";` [download] or alternately change your working directory with chdir. You might also simplify your life by using File::Find. #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.	[reply] [d/l] [select]
Re^2: Iterate trough a series of folders by BlueStarry (Novice) on Apr 04, 2016 at 18:32 UTC
Thank you very much for your advice sir, it works, but i'm struggling understanding why yours works and mine not. By the way, your help is much appreciated.	[reply]
Re^3: Iterate trough a series of folders by kennethk (Abbot) on Apr 04, 2016 at 18:52 UTC
Using `"$dir/$_"` changes your paths from relative to absolute. Unless your working directory (the directory your shell was in when you executed perl) is equal to `$dir`, -d will be looking in the wrong place. This might be more obvious if you execute the code: `#!/usr/bin/perl use strict; use warnings; use 5.10.0; my $dir = "C:/Users/ST/DesktopSample"; opendir (my $gdh, $dir) or die "Unable to open main directory"; say for readdir($gdh); closedir($gdh);` [download] #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.	[reply] [d/l] [select]
Re: Iterate trough a series of folders by 1nickt (Canon) on Apr 04, 2016 at 18:56 UTC
You can use Path::Tiny for this: `#!/usr/bin/perl use strict; use warnings; use Path::Tiny qw/ path /; my $dir = "C:/Users/ST/DesktopSample"; my $iterator = path( $dir )->iterator({ recurse => 1, follow_symlinks => 0, }); while ( my $path = $iterator->() ) { if ( path( $path )->is_dir ) { ... } if ( path( $path )->is_file ) { ... } }` [download] The iterator will automatically skip `.` and `..` Hope this helps! The way forward always starts with a minimal test.	[reply] [d/l] [select]
Re: Iterate trough a series of folders by Laurent_R (Canon) on Apr 04, 2016 at 18:56 UTC
You might want to use the glob function, which simplifies significantly what you are trying to do: it preserves the path of the files and removes the `.` and `..` pseudo directories. `my @dirs = grep {-d} glob ("$path/*");` [download]	[reply] [d/l] [select]
Re: Iterate trough a series of folders by Marshall (Canon) on Apr 04, 2016 at 18:13 UTC
readdir will return the directories without complete path. the "." and ".." are also returned just like if you did ls or dir under windows. "." is current dir, and ".." is previous directory. You need to filter those out. grep {!/^./ and -d $_}readdir; if you have "hidden directories that start with "." and you want them, then modify grep accordingly.	[reply]
Re: Iterate trough a series of folders by FreeBeerReekingMonk (Deacon) on Apr 04, 2016 at 18:25 UTC
I am unsure this works in Windows (as it probably uses the shell expansion), but try this: `@tumorfiles = sort <C:/Users/ST/DesktopSample//>;` [download] Where that * can be as complex as `<C:/Users/ST/DesktopSample/TUMOR-/.dat>`	[reply] [d/l] [select]
Re^2: Iterate trough a series of folders by Discipulus (Canon) on Apr 05, 2016 at 07:32 UTC
I confirm that this works even on windows (but only with `/` as path separator: see File::Glob notes). i must admit i never used this construct (but directly glob ). it is described in the IO operators `perl -E "say for sort <.//.pm>" \| grep -c . 4` [download] See also Re: Searching for specific text for more examples and the difference between iterative and recursive solutions. L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]