John W. Krahn wrote:
e-letter wrote:
Readers,
Hello,
I have a csv file (greater than 256 columns hence unable to open in
spreadsheet) of the following format:
column header1, column header2, column header3
1,0.0e0,0.0e0,5e-6
2,0.0e0,0.0e0,6e-7
3,0.0e0,0.0e0,0.0e0
I want to perform: "if column headerx contains only values of 0.0e0,
delete the column (including the column header).
How do I start please?
This may work for you:
#!/usr/bin/perl
use warnings;
use strict;
use Fcntl ':seek';
@ARGV = 'somefile.csv';
$^I = '.back';
my @headers = map 1, split /,/, <>, -1;
my @keep = ( undef ) x @headers;
while ( <> ) {
chomp;
my @fields = split /,/, $_, -1;
for my $i ( 0 .. $#fields ) {
$keep[ $i ] = $i if $fields[ $i ] ne '0.0e0';
}
last if @headers == grep defined, @keep;
That would probably be more efficient as:
exit 0 if @headers == grep defined, @keep;
}
@keep = grep defined, @keep;
seek ARGV, 0, SEEK_SET or die "Cannot seek on '$ARGV' $!";
while ( <> ) {
chomp;
print join( ',', ( split /,/, $_, -1 )[ @keep ] ), "\n";
}
__END__
John
--
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order. -- Larry Wall
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