Construct a hash from a log file. 2

whn · Apr 1, 2013

A sample log file somewhat look like this:

Code:

x11:x12:x13:...:x1m:value1
x21:x22:x23:...:x2m:...:x2n:value2
x31:x32:x33:...:x3i:value3
x41:x42:x43:...:x4i:...:x4j:value4

Note that --
1) In each row, the elements are delimited by ':';
2) The number of elements in each row may very, i.e. m, n, i, & j are integers and m != n != i != j.

How to construct a multi-dimension hash whose keys are the elements in rows denoted as xij and values are the last element in each row.

For instance, if a simplified log file was like:

Code:

x11:x12:x13:value1
x21:x22:x23:x24:value2

then the hash would be like:

Code:

my %cache => (
    'x11'=>{
        'x12'=>{
            'x13'=>value1,
        },
    },
    'x21'=>{
        'x22'=>{
            'x23'=>{
                'x24'=>value2,
                },
            },
        },
    },
);

I guess the implementation should use recursive call. But I don't know how to implement it.

Thanks for your kind help.

feherke · Apr 2, 2013

Hi

No need for recursion, a simple loop is enough :

Perl:

[b]use[/b] Data[teal]::[/teal]Dumper[teal];[/teal]

[b]my[/b] [navy]%cache[/navy][teal] = ();[/teal]

[b]while[/b] [teal]([/teal][b]chomp[/b][teal]([/teal][b]my[/b] [navy]$line[/navy] [teal]=[/teal] [green][i]<DATA>[/i][/green][teal]))[/teal] [teal]{[/teal]
  [b]my[/b] [navy]@field[/navy] [teal]=[/teal] [b]split[/b] [green][i]/:/[/i][/green][teal],[/teal] [navy]$line[/navy][teal];[/teal]

  [b]my[/b] [navy]$parent[/navy] [teal]=[/teal] [teal]\[/teal][navy]%cache[/navy][teal];[/teal]
  [b]for[/b] [teal]([/teal][b]my[/b] [navy]$i[/navy] [teal]=[/teal] [purple]0[/purple][teal],[/teal] [navy]$l[/navy] [teal]=[/teal] scalar [navy]@field[/navy][teal];[/teal] [navy]$i[/navy] [teal]<[/teal] [navy]$l[/navy] [teal]-[/teal] [purple]2[/purple][teal];[/teal] [navy]$i[/navy][teal]++)[/teal] [teal]{[/teal]
    [navy]$parent[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal][teal]}[/teal] [teal]=[/teal] [teal]{}[/teal] [b]unless[/b] [b]defined[/b] [navy]$parent[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal][teal]}[/teal][teal];[/teal]
    [navy]$parent[/navy] [teal]=[/teal] [navy]$parent[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal][teal]}[/teal][teal];[/teal]
  [teal]}[/teal]
  [navy]$parent[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][-[/teal][purple]2[/purple][teal]][/teal][teal]}[/teal] [teal]=[/teal] [navy]$field[/navy][teal][-[/teal][purple]1[/purple][teal]];[/teal]
[teal]}[/teal]

[b]print[/b] Dumper [teal]\[/teal][navy]%cache[/navy][teal];[/teal]

__DATA__
x11:x12:x13:value1
x21:x22:x23:x24:value2

Code:

$VAR1 = {
          'x11' => {
                     'x12' => {
                                'x13' => 'value1'
                              }
                   },
          'x21' => {
                     'x22' => {
                                'x23' => {
                                           'x24' => 'value2'
                                         }
                              }
                   }
        };

Feherke.
[link feherke.github.com/]

http://feherke.github.com/

[/url]

whn · Apr 2, 2013

Hi Feherke,

Thank you so much for your help!!

But I have some follow-up questions. At first, please take a look at my modified code and input data.

Perl:

#!/usr/bin/perl -w

use strict;
use warnings;
use Data::Dumper;

my %cache = ();

while (chomp(my $line = <DATA>)) { [b] # This is line 9[/b]
  if($line !~ /^#/) {
    my @field = split /:/, $line;

    my $parent = \%cache;
    for (my $i = 0, my $l = scalar @field; $i < $l - 2; $i++) {
      $parent->{$field[$i]} = {} unless defined $parent->{$field[$i]};
      $parent = $parent->{$field[$i]};
    }
    if($field[-2]) { [b]# To filter NULL strings
      # But would it also filter out 0 - zero's? [/b]
      $parent->{$field[-2]} = $field[-1];
    }
  }
}

print Dumper \%cache;

__DATA__
# the 2nd element is NULL
x11::x13:value1
# the 2nd element is zero
x21:0:x23:x24:value2
x31:x32:value3

The actual output:

Code:

% ./readCache.pl
[COLOR=red]Use of uninitialized value $line in chomp at ./readCache.pl line 9, <DATA> line 5.[/color]
$VAR1 = {
          'x11' => {
                     '' => {
                             'x13' => 'value1'
                           }
                   },
          'x31' => {
                     'x32' => 'value3 '
                   },
          'x21' => {
                     '0' => {
                              'x23' => {
                                         'x24' => 'value2 '
                                       }
                            }
                   }
        };

The output I want:

Code:

$VAR1 = {
          'x11' => {
                     'x13' => 'value1'
                   },
          'x31' => {
                     'x32' => 'value3 '
                   },
          'x21' => {
                     '0' => {
                              'x23' => {
                                         'x24' => 'value2 '
                                       }
                            }
                   }
        };

The output I expected from my modified codes, but not I wanted:

Code:

$VAR1 = {
          'x11' => {
                     'x13' => 'value1'
                   },
          'x31' => {
                     'x32' => 'value3 '
                   },
          'x21' => {
                     'x23' => {
                                'x24' => 'value2 '
                              }
                   }
        };

My questions:
1) Where does that warning come from? How to get rid of it?
2) Why didn't my implementation get rid of --
i) the NULL string, which is what I expected and wanted;
ii) the '0', which is what I expected, but not what I wanted

feherke · Apr 2, 2013

Hi

whn said:
1) Where does that warning come from? How to get rid of it?

That is because :
[ul]
[li]You turned on warnings. ( By the way, unless you want to turn warnings on/off for certain blocks, the [tt]-w[/tt] switch and [tt]use warnings[/tt] pragma are equivalent. )[/li]
[li]Personally I prefer to enjoy Perl's flexibility and ignore warnings. Despite that I try to not force the edges too much when giving advices, there are catchy situations I miss.[/li]
[/ul]

In other words, at the end of input, the last value returned by the [tt]<>[/tt] operation is [tt]undef[/tt]. Using [tt]chomp()[/tt] on a variable with [tt]undef[/tt] value, gives that warning :

Code:

[blue]master #[/blue] perl -e 'chomp $x'

[blue]master #[/blue] perl -we 'chomp $x'
Name "main::x" used only once: possible typo at -e line 1.
Use of uninitialized value $x in scalar chomp at -e line 1.

[blue]master #[/blue] perl -e '$x=undef; chomp $x'

[blue]master #[/blue] perl -we '$x=undef; chomp $x'
Use of uninitialized value $x in scalar chomp at -e line 1.

To get rid of that warning just move the [tt]chomp()[/tt] call from the condition inside the loop :

Code:

[b]while[/b] [teal]([/teal][b]my[/b] [navy]$line[/navy] [teal]=[/teal] [green][i]<DATA>[/i][/green][teal])[/teal] [teal]{[/teal]  [gray]# This is line 9[/gray]
  [b]chomp[/b] [navy]$line[/navy][teal];[/teal]

whn said:
2) Why didn't my implementation get rid of --

i) the NULL string, which is what I expected and wanted;

In that DATA line the field indexes are
[pre]
[gray][highlight #fcc]0 [/highlight] [highlight]1 [/highlight] [highlight #cfc]2 [/highlight] [highlight #ccf]3 [/highlight] # from left[/gray]
[highlight #fcc]x11[/highlight] : : [highlight #cfc]x13[/highlight] : [highlight #ccf]value1[/highlight]
[gray][highlight #fcc]-4 [/highlight] [highlight]-3[/highlight] [highlight #cfc]-2 [/highlight] [highlight #ccf]-1 [/highlight] # from right[/gray]
[/pre]

Even more, you tested after the loop, in that moment the key with the empty string was already created.

Better handle it on [tt]split()[/tt] by splitting not on each colon ( : ), but on one or more consecutive colons :

Code:

  [b]my[/b] [navy]@field[/navy] [teal]=[/teal] [b]split[/b] [green][i]/:[highlight]+[/highlight]/[/i][/green][teal],[/teal] [navy]$line[/navy][teal];[/teal]

whn said:
ii) the '0', which is what I expected, but not what I wanted

Similarly, in that DATA line '0' was at index -4, not the tested one.

One minor thing. I find that instructions which condition the execution of the loop body are better to do [tt]next[/tt] ( or [tt]continue[/tt] in other languages ) then to control a huge block enclosing the entire loop block.

So finally I this is what I have now :

Perl:

[gray]#!/usr/bin/perl -w[/gray]

[b]use[/b] strict[teal];[/teal]
[b]use[/b] warnings[teal];[/teal]
[b]use[/b] Data[teal]::[/teal]Dumper[teal];[/teal]

[b]my[/b] [navy]%cache[/navy] [teal]=[/teal] [teal]();[/teal]

[b]while[/b] [teal]([/teal][b]my[/b] [navy]$line[/navy] [teal]=[/teal] [green][i]<DATA>[/i][/green][teal])[/teal] [teal]{[/teal]  [gray]# This is line 9[/gray]
  [b]chomp[/b] [navy]$line[/navy][teal];[/teal]
  [highlight #ffc][b]next[/b] [b]if[/b] [navy]$line[/navy] [teal]=~[/teal] [green][i]/^#/[/i][/green][teal];[/teal][/highlight]

  [b]my[/b] [navy]@field[/navy] [teal]=[/teal] [b]split[/b] [green][i]/:+/[/i][/green][teal],[/teal] [navy]$line[/navy][teal];[/teal]

  [b]my[/b] [navy]$parent[/navy] [teal]=[/teal] [teal]\[/teal][navy]%cache[/navy][teal];[/teal]
  [b]for[/b] [teal]([/teal][b]my[/b] [navy]$i[/navy] [teal]=[/teal] [purple]0[/purple][teal],[/teal] [b]my[/b] [navy]$l[/navy] [teal]=[/teal] scalar [navy]@field[/navy][teal];[/teal] [navy]$i[/navy] [teal]<[/teal] [navy]$l[/navy] [teal]-[/teal] [purple]2[/purple][teal];[/teal] [navy]$i[/navy][teal]++)[/teal] [teal]{[/teal]
    [navy]$parent[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal][teal]}[/teal] [teal]=[/teal] [teal]{}[/teal] [b]unless[/b] [b]defined[/b] [navy]$parent[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal][teal]}[/teal][teal];[/teal]
    [navy]$parent[/navy] [teal]=[/teal] [navy]$parent[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal][teal]}[/teal][teal];[/teal]
  [teal]}[/teal]
  [navy]$parent[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][-[/teal][purple]2[/purple][teal]][/teal][teal]}[/teal] [teal]=[/teal] [navy]$field[/navy][teal][-[/teal][purple]1[/purple][teal]];[/teal]
[teal]}[/teal]

[b]print[/b] Dumper [teal]\[/teal][navy]%cache[/navy][teal];[/teal]

__DATA__
# the 2nd element is NULL
x11::x13:value1
# the 2nd element is zero
x21:0:x23:x24:value2
x31:x32:value3

Feherke.
[link feherke.github.com/]

http://feherke.github.com/

[/url]

whn · Apr 2, 2013

You're the man, Feherke. Many thanks!!

whn · May 22, 2013

At first, my sincere thanks go to Feherke! With his help I have used the implementation suggested by Feherke a few times at work. They are all working very well. But it encountered a problem lately that I cannot understand it at all.

Hence I constructed an example to show the problem that I am having now. Below is my sample code (a bit long, 63 lines):

Code:

#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my $log = '/tmp/log';
my $dlmt = '_';
my $tail = 't';
my @ver = (3, 3.22, 5.15, 5.16, '5.2.33', 5);
[b]@ver = (3.22, 3.3, '4.4.4.4', '3.5.21', 6, 4); [COLOR=#CC0000]# this is line 11[/color].
# comment out this line in 2nd run[/b]
print Dumper(@ver);
&cacheIt(\@ver);
my $info = &readCache();
print Dumper($info);
exit;

sub readCache {
  my %cache = ();
  open(RH, "$log");
  my $lineCnt = 1;
  my $key;
  while(my $line = <RH>) {
    chomp($line);
    if($line =~ /$dlmt/) {
      my @field = split(/$dlmt/, $line);
      my $parent = \%cache;
      my $l = scalar @field;
      for (my $i = 0; $i < $l - 2; $i++) {
        $parent->{$field[$i]} = {} unless exists $parent->{$field[$i]};
        $parent = $parent->{$field[$i]};
      }
      if($#field > 1) {
        $parent->{$field[-2]} = $field[-1]; [b][COLOR=#EF2929]# This is line 35[/color][/b]
      }
      else {
        if(!exists($parent->{$field[-2]})) {
          $parent->{$field[-2]} = $field[-1];
        }
      }
    } # end of if($line =~ /$dlmt/)
    else {
      $key = $line;
    }
    $lineCnt++;
  } # end of while(my $line = <RH>)
  return \%cache;
}

sub cacheIt {
  my $a = $_[0];
  my %h;
  my $hRef = \%h;
  open(WH, ">$log");
  for(my $i = 0; $i <= $#$a; $i++) {
    my @tmp = split(/\./, $a->[$i]);
    my $str = join $dlmt, @tmp;
    $str .= $dlmt.$tail;
    print WH $str."\n";
  }
  close(WH);
}

The output from first run. Line 11 is taking effect.
Everything is expected.

Code:

./test.pl
$VAR1 = '3.22';
$VAR2 = '3.3';
$VAR3 = '4.4.4.4';
$VAR4 = '3.5.21';
$VAR5 = 6;
$VAR6 = 4;
$VAR1 = {
          '6' => 't',
          '4' => {
                   '4' => {
                            '4' => {
                                     '4' => 't'
                                   }
                          }
                 },
          '3' => {
                   '22' => 't',
                   '3' => 't',
                   '5' => {
                            '21' => 't'
                          }
                 }
        };

Below is the output from 2nd run. Line 11 is commented out.

Code:

./test.pl
$VAR1 = 3;
$VAR2 = '3.22';
$VAR3 = '5.15';
$VAR4 = '5.16';
$VAR5 = '5.2.33';
$VAR6 = 5;
[b]Can't use string ("t") as a HASH ref while "strict refs" in use [COLOR=#EF2929]at ./test.pl line 35[/color], <RH> line 2.[/b]

I may have more questions to follow. But let me stop here for now.
Thank you so much for your time and help.

prex1 · May 22, 2013

It seems that in the 2nd run you are reading a file that was created by [tt]cacheIt()[/tt] in the 1st run. Can you give us the content of that file (at least line 2)?

http://www.xcalcs.com

: Online engineering calculations

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

whn · May 22, 2013

Hi prex,

Thanks for your post. After having read your post, I know what's wrong. But I don't know how to fix it, yet.

Below is my updated codes. The code in blue are new. Please also note that the line numbers changed too.

Code:

#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my $log = '/tmp/log';
my $dlmt = '_';
my $tail = 't';
[b][COLOR=#3465A4]my @ver = (3, 3.22, '5.2.33', 5, 6); # The 1st element '3' breaks the code
#@ver = (3.22, '5.2.33', 5, 6); # this is line 11.
# comment out line 11 in 2nd run[/color][/b]
print Dumper(@ver);
&cacheIt(\@ver); 
[COLOR=#3465A4][b]my $logFileContents = `cat $log`;
print "Log File Contents:\n$logFileContents\n\n";[/b][/color]
my $info = &readCache();
print Dumper($info);
exit;

sub readCache {
  my %cache = ();
  open(RH, "$log");
  my $lineCnt = 1;
  my $key;
  while(my $line = <RH>) {
    chomp($line);
    if($line =~ /$dlmt/) {
      my @field = split(/$dlmt/, $line);
      my $parent = \%cache;
      my $l = scalar @field;
      for (my $i = 0; $i < $l - 2; $i++) {
        $parent->{$field[$i]} = {} unless exists $parent->{$field[$i]};
        $parent = $parent->{$field[$i]};
      }
      if($#field > 1) {
        $parent->{$field[-2]} = $field[-1]; [COLOR=#CC0000][b]# This is line 37[/b][/color]
      }
      else {
        if(!exists($parent->{$field[-2]})) {
          $parent->{$field[-2]} = $field[-1];
        }
      }
    } # end of if($line =~ /$dlmt/)
    else {
      $key = $line;
    }
    $lineCnt++;
  } # end of while(my $line = <RH>)
  return \%cache;
}

sub cacheIt {
  my $a = $_[0];
  my %h;
  my $hRef = \%h;
  open(WH, ">$log");
  for(my $i = 0; $i <= $#$a; $i++) {
    my @tmp = split(/\./, $a->[$i]);
    my $str = join $dlmt, @tmp;
    $str .= $dlmt.$tail;
    print WH $str."\n";
  }
  close(WH);
}

First run. Line 11 takes effect:

Code:

% ./test.pl
$VAR1 = '3.22';
$VAR2 = '5.2.33';
$VAR3 = 5;
$VAR4 = 6;
Log File Contents:
3_22_t
5_2_33_t
5_t
6_t


$VAR1 = {
          '6' => 't',
          '3' => {
                   '22' => 't'
                 },
          '5' => {
                   '2' => {
                            '33' => 't'
                          }
                 }
        };

Second run. Line 11 is commented out:

Code:

./test.pl
$VAR1 = 3;
$VAR2 = '3.22';
$VAR3 = '5.2.33';
$VAR4 = 5;
$VAR5 = 6;
Log File Contents:
3_t
3_22_t
5_2_33_t
5_t
6_t


[b][COLOR=#EF2929]Can't use string ("t") as a HASH ref while "strict refs" in use at ./test.pl line 37, <RH> line 2.[/color][/b]

whn · May 22, 2013

Ok, I fixed the problem - it's somewhat like a hack.

The code is simplified and the blue part is new and looks like a hack to me. I'd appreciate that if someone could polish it.

Thanks!

Code:

#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my $tail = 't';
[COLOR=#CC0000]my @ver = (3, 3.22, '5.2.33', 5, 6); # this is line 8.
#@ver = (3.22, '5.2.33', 5, 6); # this is line 9.
# Either line 8 or line 9 would work!![/color]
my $info = &a2h(\@ver);
print Dumper($info);
exit;

sub a2h {
  my $a = $_[0];
  my %h = ();
  my @buf;
  foreach my $x (@{$a}) {
    my @field = split(/\./, $x);
    my $last = $#field + 1;
    $field[$last] = $tail;
    my $hRef = \%h;
    my $l = scalar @field;
    for (my $i = 0; $i < $l - 2; $i++) {
      $hRef->{$field[$i]} = {} unless exists $hRef->{$field[$i]};
      $hRef = $hRef->{$field[$i]};
    }
    if($#field > 1) {
      $hRef->{$field[-2]} = $field[-1];
    }
    else {
      push @buf, $x;
    }
  } # end of while(my $line = <RH>)
  [COLOR=#3465A4]if(@buf) {
    foreach my $x (@buf) {
      my @field = split(/\./, $x);
      my $last = $#field + 1;
      $field[$last] = $tail;
      my $hRef = \%h;
      if(!exists($hRef->{$field[0]})) {
        $hRef->{$field[0]} = $field[1];
      }
    } # end of foreach my $x (@buf)
  } # end of if(@buf)[/color]
  return \%h;
}

And the output:

Code:

% ./test.pl
$VAR1 = {
          '6' => 't',
          '3' => {
                   '22' => 't'
                 },
          '5' => {
                   '2' => {
                            '33' => 't'
                          }
                 }
        };

prex1 · May 22, 2013

In your last but one post, with line 10 in effect, in line 1 of log file you create [tt]$cache{3}='t'[/tt], then in line 2, with
[tt]$parent = $parent->{$field[$i]}[/tt]
where [tt]$i=0[/tt] and [tt]$field[$i]=3[/tt],
you set [tt]$parent='t'[/tt] and this is what perl doesn't like, when [tt]$parent[/tt] is then used as a reference.
Having not read the whole thread, it is unclear to me what is the logic of what you are trying to do; also your code is difficult to read with how you use references. You should restart from the scratch with a more readable code.

http://www.xcalcs.com

: Online engineering calculations

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

feherke · May 23, 2013

Hi

Personally I followed the beginning of this thread, but now I am abit lost. So I just rewrote this dumbly. As your crashes on [tt][navy]@ver[/navy] [teal]=[/teal] [teal]([/teal][green]'1'[/green][teal],[/teal] [green]'1.2'[/green][teal],[/teal] [green]'1.2.3'[/green][teal]);[/teal][/tt] I decided to not reproduce it exactly.

Perl:

[gray]#!/usr/bin/perl[/gray]

[b]use[/b] strict[teal];[/teal]
[b]use[/b] warnings[teal];[/teal]
[b]use[/b] Data[teal]::[/teal]Dumper[teal];[/teal]

[b]my[/b] [navy]$tail[/navy] [teal]=[/teal] [green][i]'t'[/i][/green][teal];[/teal]
[b]my[/b] [navy]@ver[/navy] [teal]=[/teal] [teal]([/teal][purple]3[/purple][teal],[/teal] [purple]3.22[/purple][teal],[/teal] [green][i]'5.2.33'[/i][/green][teal],[/teal] [purple]5[/purple][teal],[/teal] [purple]6[/purple][teal]);[/teal]
[b]my[/b] [navy]$info[/navy] [teal]=[/teal] [teal]&[/teal][COLOR=darkgoldenrod]a2h[/color][teal](\[/teal][navy]@ver[/navy][teal]);[/teal]
[b]print[/b] [COLOR=darkgoldenrod]Dumper[/color][teal]([/teal][navy]$info[/navy][teal]);[/teal]

[b]sub[/b] a2h [teal]{[/teal]
  [b]my[/b] [navy]$a[/navy] [teal]=[/teal] [navy]$_[/navy][teal][[/teal][purple]0[/purple][teal]];[/teal]
  [b]my[/b] [navy]%h[/navy] [teal]=[/teal] [teal]();[/teal]
  [b]my[/b] [navy]@buf[/navy][teal];[/teal]
  [b]foreach[/b] [b]my[/b] [navy]$x[/navy] [teal]([/teal]@[teal]{[/teal][navy]$a[/navy][teal]}[/teal][teal])[/teal] [teal]{[/teal]
    [b]my[/b] [navy]@field[/navy] [teal]=[/teal] [b]split[/b][teal]([/teal][green][i]/\./[/i][/green][teal],[/teal] [navy]$x[/navy][teal]);[/teal]
    [b]my[/b] [navy]$hRef[/navy] [teal]=[/teal] [teal]\[/teal][navy]%h[/navy][teal];[/teal]
    [b]my[/b] [navy]$hPrev[/navy][teal];[/teal]
    [b]my[/b] [navy]$l[/navy] [teal]=[/teal] scalar [navy]@field[/navy][teal];[/teal]
    [b]for[/b] [teal]([/teal][b]my[/b] [navy]$i[/navy] [teal]=[/teal] [purple]0[/purple][teal];[/teal] [navy]$i[/navy] [teal]<[/teal] [navy]$l[/navy][teal];[/teal] [navy]$i[/navy][teal]++)[/teal] [teal]{[/teal]
      [navy]$hPrev[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy] [teal]-[/teal] [purple]1[/purple][teal]][/teal][teal]}[/teal] [teal]=[/teal] [navy]$hRef[/navy] [teal]=[/teal] [teal]{}[/teal] [b]unless[/b] [b]ref[/b] [navy]$hRef[/navy] [b]eq[/b] [green][i]'HASH'[/i][/green][teal];[/teal]
      [navy]$hRef[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal][teal]}[/teal] [teal]=[/teal] [navy]$i[/navy] [teal]<[/teal] [navy]$l[/navy] [teal]-[/teal] [purple]1[/purple] [teal]?[/teal] [teal]{}[/teal] [teal]:[/teal] [navy]$tail[/navy] [b]unless[/b] [b]exists[/b] [navy]$hRef[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal][teal]}[/teal][teal];[/teal]
      [navy]$hPrev[/navy] [teal]=[/teal] [navy]$hRef[/navy][teal];[/teal]
      [navy]$hRef[/navy] [teal]=[/teal] [navy]$hRef[/navy][teal]->[/teal][teal]{[/teal][navy]$field[/navy][teal][[/teal][navy]$i[/navy][teal]][/teal][teal]}[/teal][teal];[/teal]
    [teal]}[/teal]
  [teal]}[/teal]
  [b]return[/b] [teal]\[/teal][navy]%h[/navy][teal];[/teal]
[teal]}[/teal]

I know, not much readable. So no hard feelings if you prefer to not use it.

Feherke.
feherke.github.io

whn · May 23, 2013

To Feherke,

Actually, I like it a lot and have learned a lot from your posts, including this one!

Thank you very much. Best regards to you.

To prex,

I have already realized what was wrong after I read your first response. Thank you.

>it is unclear to me what is the logic of what you are trying to do
I know and I am sorry. In my first post in this thread, I said what I was trying to accomplish. With Feherke's help, I have achieved my goal.

Then I started to work on a new problem and I thought I cold leverage what I learned from Feherke's post in this thread.

Then I got this error: Can't use string ("t") as a HASH ref while "strict refs" in use at ./test.pl line 37, <RH> line 2.

So I decided to ask for help again in this thread w/o clearly explaining what my goal is. Sorry about this.

With Feherke's help, I have made a little progress. But I have further questions which I'll ask for your help in a new thread today or tomorrow (Time Zone: US EDT).

Sorry for the confusion and thank you so much for your time and help.

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Construct a hash from a log file. 2

whn

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feherke

Programmer

whn

Programmer

feherke

Programmer

whn

Programmer

whn

Programmer

prex1

Programmer

whn

Programmer

whn

Programmer

prex1

Programmer

feherke

Programmer

whn

Programmer

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