134 lines
2.8 KiB
Perl
Executable file
134 lines
2.8 KiB
Perl
Executable file
#!/usr/bin/perl
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=pod
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=head1 NAME
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field - select fields in tabular files
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=head1 SYNOPSIS
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B<field> I<field spec> file
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... | B<field> I<field spec>
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=head1 DESCRIPTION
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B<field> selects fields in tabular files.
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=head1 EXAMPLE
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Select field 2:
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field 2 file
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Select field 2,3,4,5:
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field 2-5 file
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Select field 2..end:
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field 2- file
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Select field 2,3,4,1:
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field 2-4,1 file
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=head1 AUTHOR
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Copyright (C) 2017-2020 Ole Tange,
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http://ole.tange.dk and Free Software Foundation, Inc.
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=head1 LICENSE
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Copyright (C) 2012 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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at your option any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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=head1 SEE ALSO
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B<cut>
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=cut
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use strict;
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my @fields = range_to_fields(shift);
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my $fields = join(",", @fields);
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sub range_to_fields {
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my @ranges = split(/,/, shift);
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my @fields;
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for (@ranges) {
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/^(\d+)$/ and push (@fields,($1-1));
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/^(\d+)-(\d+)$/ and push (@fields,($1-1) .. ($2-1));
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/^(\d+)-$/ and do {
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push (@fields,($1-1)." .. \$#F");
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$Global::must_eval = 1;
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};
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}
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# Default: field 1
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# Perl counts from 0 - not from 1
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if(not @fields) { @fields=(1-1); }
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return @fields;
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}
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if($Global::must_eval) {
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while(<>) {
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my @F = split/\s+/,$_;
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if(not $Calc::f{$#F}) {
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# Eval is expensive, so only do it if we have not done before
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# If an argument ends in '-' then we must figure out the last field
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# which depends on the number of fields in the line
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$Calc::f{$#F}++;
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@{$Calc::fields->{$#F}} = eval $fields;
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}
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print join("\t",@F[@{$Calc::fields->{$#F}}]),"\n";
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}
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} else {
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# awk counts from 1 not 0
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@fields = map { $_+1 } @fields;
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# Use mawk (60 MB/s)/gawk (30 MB/s)/awk (? MB/s)
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my $awk = which("mawk") || which("gawk") || which("awk");
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my $awkscript = 'BEGIN {OFS = "\t"} {print '.
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(join ",", map { '$'.$_ } @fields).
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'}';
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exec($awk,$awkscript);
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}
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sub which {
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# Input:
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# @programs = programs to find the path to
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# Returns:
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# @full_path = full paths to @programs. Nothing if not found
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my @which;
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for my $prg (@_) {
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push(@which, grep { not -d $_ and -x $_ }
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map { $_."/".$prg } split(":",$ENV{'PATH'}));
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if($prg =~ m:/:) {
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# Including path
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push(@which, grep { not -d $_ and -x $_ } $prg);
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}
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}
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return wantarray ? @which : $which[0];
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}
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