Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks!

I am trying to process the data for all the files I am reading from a directory, but I need to know how many fields are in each file before going into the foreach loop.
My goal is, if there are 4 values in the first row of the file file2.csv the push should be like: 
     push @all, [
      
        $rows->[0],
        $rows->[1],
            $rows->[2],
        $rows->[3],
        ];

[download]
and so on for the rest of the files I am reading in depending on how many values are in each row of each file .
All the other rows in each file will have the same number of values as the first row.

I have this code where you can see what I am trying to do: 
#!/usr/bin/perl

use strict;
use warnings;

use Data::Dump 'pp';
use Data::Dumper;
use Text::CSV;

my $csv = Text::CSV->new ( { binary => 1, eol => "\n",  quote_char => 
+'', } )
    or die "Cannot use CSV: ".Text::CSV->error_diag ();

my @files = qw( file1.csv file2.csv file3.csv file4.csv file5.csv );

# I need to read all the files in @files once at a time
my ($read_file, $name) = read_file(file => $files[0],);

my ( $ready, $file_name ) = is_ready( do_data => $read_file, fname =>$
+name);
                 
print "$file_name:\n\n";
print Dumper $ready;

sub read_file {

 my (%args) = @_;

 my $file = $args{ file };
 
 my $fh;
 eval {
   open $fh, '<:encoding(utf8)', "dir/$file" or die "Could not open '$
+file' $!\n";
 };
 
  if ($@) {
    warn "Error opening $file";
  }

  my @data;
  while (my $rows = $csv->getline( $fh )) {
    push @data,  $rows;
  }

 if (not $csv->eof) {
   $csv->error_diag();
 }
     
 close $fh;

 return \@data, $file;
    
}


sub is_ready {

 my (%args) = @_;

 my $data  = $args{ do_data };
 my $fname = $args{ fname };
 
 my @all;
 # Need to process $data for all the files coming in, but
 # I have to know how many fields are in each file before going into
 # the foreach loop.
 # If there are 4 values in the file file2.csv the push should be like
+:
=code
     push @all, [
        $rows->[0],
        $rows->[1],
            $rows->[2],
        $rows->[3],
            ];
=cut
 # and so on for the rest of the file.
 
 foreach my $rows ( @{ $data } ) {


   push @all, [
      
        $rows->[0],
        $rows->[1],
            $rows->[2],
        ...
        ];
        
  }

   my $send = \@all;

 return $send, $fname;

} #


=data

file1.csv  = 9 values in each row: eg. one,two,three,four,five,six,sev
+en,eight,nine

file2.csv  = 4 values in each row eg. one,two,three,four

file3.csv = 10 values in each row eg. one,two,three,four,five,six,seve
+n,eight,nine,ten

file4.csv = 7 values in each row eg.  one,two,three,four,five,six,seve
+n

file5.csv = 5 values in each row eg. one,two,three,four,five

[download]
Thanks for helping out if possible!

Replies are listed 'Best First'.
Re: Pushing rows of data into array
by Marshall (Canon) on Apr 18, 2016 at 22:30 UTC
    I got a little lost in what you are trying to do. But looks like you are going to get a reference to an Array of Array. You don't want to "flatten" this out. It will be easier to process each row if you maintain this structure. See: http://perldoc.perl.org/5.8.8/perldsc.html#ARRAYS-OF-ARRAYS.

    Here is some example code: 

    #!/usr/bin/perl 
use warnings;
use strict;
use Data::Dumper;

my @data = ([qw/one two three four five/],  #array of array
            [qw/ a   b    c    d     e/],);
            
my $dataref = \@data;

my @all;
push @all,@$dataref;  #not sure of need for this? but works.

print Dumper \@all;

print scalar @{$dataref->[0]},"\n"; #number of elements in row[0]
                                    # i.e. "5"
print $dataref->[0][1],"\n";        #prints "two", 2nd element of row 
+0

foreach my $element (@{$dataref->[0]}) #each element of row [0]
{
   print "$element ";
}
print "\n\n";

foreach my $row_ref (@all)  #deal with references to rows
{
   print "number of elements = ".scalar @$row_ref,"  @$row_ref\n";
   # of course number of elements will be the same in each row,
   #so only need to check for row[0] as above

}

__END__
$VAR1 = [
          [
            'one',
            'two',
            'three',
            'four',
            'five'
          ],
          [
            'a',
            'b',
            'c',
            'd',
            'e'
          ]
        ];
5
two
one two three four five 

number of elements = 5  one two three four five
number of elements = 5  a b c d e

    [download]
    To find "how many columns", check the number of elements that are in the row 0 of the data array.
[reply]
[d/l]
Re: Pushing rows of data into array
by Anonymous Monk on Apr 18, 2016 at 20:43 UTC 
    push @all, @{ $rows }[0 .. $n-1]; # for appropriate $n

    [download]
[reply]
[d/l]

      Why not just
          push @all, @$rows;
      and forget about $n?

      Give a man a fish:  <%-{-{-{-<

[reply]
[d/l]
[select]
      How would you get the value for $n?
[reply]
[reply]
[d/l]
Re: Pushing rows of data into array
by BillKSmith (Monsignor) on Apr 19, 2016 at 13:50 UTC
    This suggestion is similar to Marshall's but starting with a CSV file. 
    use strict;
use warnings;
use Data::Dumper;
my @headers = split /\s/, <DATA>;
print Dumper \@headers;
my $length = @headers;
my @all;
while (my $line = <DATA>){
    my $row = [split /\s/, $line, $length];
    push @all, $row;
}
print Dumper \@all;
__DATA__
col1 col2 col3 col4
a b c d
1 2 3 4

    [download]
    Bill
[reply]
[d/l]

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