Re^2: Reformat Text File

This assumes that the keys are in sorted order to begin with and that it's easy to re-sort them. Instead, you might want to preserve the original order as much as possible.

my %result;
my @keys;
while (<>) {
  chomp;
  my ($k, $v) = split /,/;
  push @keys,$k if (!exists $result{$k});
  push @{$result{$k}}, $v;
}
for (@keys) {
  print join(",", $_, @{$result{$_}}), "\n";
}
[download]

Comment on Re^2: Reformat Text File Download Code

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Re^3: Reformat Text File by gaal (Parson) on Oct 05, 2004 at 16:37 UTC
> This assumes that the keys are in sorted order What makes you say that?	[reply]
Re^4: Reformat Text File by ikegami (Patriarch) on Oct 05, 2004 at 17:36 UTC
`bah,valueA foo,valueB foo,valueC bar,valueD` [download] results in `bah,valueA bar,valueD foo,valueB,valueC` [download] and not `bah,valueA foo,valueB,valueC bar,valueD` [download] Therefore, merlyn assumes they are sorted (or assumes the order of the lines in the result doesn't matter, but then why call sort?).	[reply] [d/l] [select]
Re^4: Reformat Text File by tall_man (Parson) on Oct 05, 2004 at 20:17 UTC
I presume the problem has been simplified from an original case with meaningful keys in some meaningful order. Say the keys were dates in some odd format: `July 21,Milestone meeting August 3,First walkthrough August 3,Committee meeting September 12,Second walkthrough` [download] merlyn puts all the values into a hash and then does a straight sort on the keys. That would make "August 3" come before "July 21" in my example. Rather than work out a fancy sorting routine for dates (or whatever the keys might be), my example maintains the original order of the first appearance of each key.	[reply] [d/l]