From: "Perl" <[EMAIL PROTECTED]>
> This should work (but beware - it is untested :)
>
> Rob
>
> my @required = qw(head1 head6 head8);
> my $line;
>
> for (<DATA>)
It's much better to use
while (<DATA>)
This "for (<DATA>)" forces Perl to read the whole file into an array
in memory. (Well ... unless the optimizer is bright enough to change
the command to "while (<DATA>)". Not sure it is. You should not
depend on the optimizer.)
> {
> chomp;
> my @field = split /,/;
While this may be fine for column headers I would not recommend doing
this with actual data. What if some of the fields are quoted and what
if they contain commas? use Text::CSV_XS instead.
"News.Support.Veritas.Com" <[EMAIL PROTECTED]> wrote
in
message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Before working with lines in a csv file I would like to check the
headers
> from the file for accuracy i.e. do the headers I expect exist, and
are
they
> in the right order.
Well then just read the first line into an array and compare it with
whatever you need.
use IO::Handle;
use Text::CSV_XS;
$csv = Text::CSV_XS->new();
open my $DATA, '< ' . $filename
or die "Can't open the file $filename : $!\n";
$headers = $csv->getline($DATA)
or die "It ain't a CSV!\n";
print "The headers found in the file are: \n\t",
join( "\n\t", @$headers),"\n";
> Alternatively, and even better, I would like to check all headers I
require
> exist, then for each parsed line extract only extract fileds that
match
the
> respective header values I want. Can anyone guide me in the best
direction
> to achieve either option.
I guess something like this could do what you want :
...
my @wanted = qw(Foo Bar Baz); # the columns you want
my @idx; # indexes of the columns in the CSV in the order
# you want them
foreach my $wanted (@wanted) {
my $found = 0;
for (my $i = 0; $i < @$headers; $i++) {
if ($wanted eq $headers->[$i]) {
push @idx, $i;
$found = 1;
last;
}
}
die "Can't find required column '$wanted' !\n"
unless $found;
}
# Eg. if $headers = [ 'Some', 'Bar', 'Other', 'Foo', 'Baz', 'XXX']
# then @idx will be set to ( 3, 1, 4)
# that is the 'Foo' is on the 3rd column (counting from zero!)
# 'Bar' on the 1st and 'Baz' on the 4th
my @data;
while (my $columns = $csv->getline($DATA)) {
@data = @$columns[@idx];
# now data contain the columns you are interested in
# and they are in the expected order
...
}
close $DATA;
HTH, Jenda
P.S.: Rob, could you change the comment part of your mail address?
It's kinda strange to see a post comming from "Perl". :-)
===== [EMAIL PROTECTED] === http://Jenda.Krynicky.cz =====
When it comes to wine, women and song, wizards are allowed
to get drunk and croon as much as they like.
-- Terry Pratchett in Sourcery
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