On Jul 13, 5:42 pm, tiago.h...@gmail.com (Tiago Hori) wrote:
> ...
> > C.DeRykus wrote:
> > There's already been a very good recommendation. But, if
> > you know your file has no irregularities, is surprise-free as
> > far as formatting, you may be tempted to just try a 1-liner
> > since Perl does make "easy things easy...":
>
> > perl -lane 'if ($F[1] ne $old ) {open($fh,'>',$F[1]) or die $!};
> > print $fh $_;$old = $F[1]' file
> I am trying to learn the CSV mode for the future, but this software will
> always spit the same file format at me, so your solution may be the way
> to go for now. Would you mi d giving me a quick explanation on what that
> one liner does? It be useful for me to learn it in more depth and be to
> adapt it to future problems.
You're welcome. As Jim says though, you're better off running a
multi-line program to learn basics if you're just beginning and only
then trying a simpler solution. Or, if you want to jump ahead, see
the doc (perldoc perlrun) to see what the switches mean.
Basically, the one-liner reads the tab-delimited file line by line
(-n); autosplits fields the line into fields based on whitespace (-
a)
and populates @F with those fields. If the 2nd column $F[1] ,
hasn't been seen or differs with the previous line's 2nd col.,
then a new output file is opened with a name matching $F[1].
The entire current line $_ is then written to the file. Lastly, $F[0]
is saved to $old so when the next line is read, $F[0] can be
compared with $old to see if a new file should be opened.
Note on switches: -l * unnecessary so can be omitted
-F\t * could be added to split on
tab instead
of whitespace
--
Charles DeRykus
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