How to print data in column form in Perl? - perl

Question

I have a program that prints the contents of arrays in rows. I would like it to print each array in a column next to each other.
This is the code:
#!/usr/local/bin/perl
use strict;
use warnings;
my #M_array;
my #F_array;
open (my $input, "<", 'ssbn1898.txt');
while ( <$input> ) {
chomp;
my ( $name, $id ) = split ( /,/ );
if ( $id eq "M" ) {
push ( #M_array, $name );
}
else {
push ( #F_array, $name );
}
}
close ( $input );
print "M: #M_array \n";
print "F: #F_array \n";
Is this possible or am I trying to do something that can't be done?
Desired format:
M F
Namem1 Namef1
Namem2 Namef2

Answer 1

You can add whatever separator you would like between your data by using the join function, the example below formats the data in your array separated by tabs:
...
use List::MoreUtils qw/pairwise/;
my $separator = "\t";
print join($separator, qw(M F)), "\n";
print join(
"\n",
pairwise { ( $a // '') . $separator . ( $b // '') } #M_array, #F_array
), "\n";
...

Answer 2

I think, you should use Perl formats. Have a look at the Perl documentation. You may want to use the #* format field in your case.
I extended your code in order to print the desired output at the end
use strict;
use warnings;
my #M_array;
my #F_array;
open (my $input, "<", 'ssbn1898.txt');
while ( <$input> ) {
chomp;
my ( $name, $id ) = split ( /,/ );
if ( $id eq "M" ) {
push ( #M_array, $name );
}
else {
push ( #F_array, $name );
}
}
close ( $input );
unshift #M_array, 'M';
unshift #F_array, 'F';
my $namem;
my $namef;
my $max = 0;
$max = (length($_) gt $max ? length($_) : $max) for #M_array;
my $w = '#' . '<' x $max;
eval "
format STDOUT =
$w #*
\$namem, \$namef
.
";
while ( #M_array or #F_array) {
$namem = shift #M_array || '';
$namef = shift #F_array || '';
write;
}

Answer 3

join is probably the simplest approach to take tabs will align your columns nicely.
join ( "\t", #array ),
Alternatively, perl allows formatting via (s)printf:
printf ( "%-10s %-10s", "first", "second" );
Or a more detailed 'format'
Given what you're trying to do is put your two arrays into columns though:
#!/usr/local/bin/perl
use strict;
use warnings;
my $format = "%-10s\t%-10s\n";
my #M_array = qw ( M1 M2 M3 M4 M5 );
my #F_array = qw ( F1 F2 F3 );
my $maxrows = $#M_array > $#F_array ? $#M_array : $#F_array;
printf ( $format, "M", "F" );
for my $rownum ( 0..$maxrows ) {
printf ( $format, $M_array[$rownum] // '', $F_array[$rownum] // '' );
}
This will print a header row, and then loop through you arrays printing one line at a time. // is a conditional operation that tests if something is defined. It's only available in newer perls though*. In older versions || will do the trick - it's almost the same, but handles '' and 0 slightly differently.
* Perl 5.10 onward, so is pretty safe, but worth mentioning because some system are still rocking around with perl 5.8 on them.

Answer 4

You may format output with the sprintf function, but there are some more problems to solve: What if the arrays don't have the same count of entries? For this, you need a place-holder. How much letters must fit into a column? How should it be aligned? Some code for illustration:
#!/usr/bin/perl
use strict;
use warnings;
my #m = (1, 2, 3);
my #f = (11, 22, 33, 44);
# calculate how many rows to display
my $max = #m;
if (#m < #f) {
$max = #f;
}
# placeholder for missing data
my $none = '-';
# formatting 20 chars per column, left aligned
my $fmt = "%-20s%-20s\n";
# print header
print sprintf($fmt, "M", "F");
# print data rows
foreach my $i (0..$max-1) {
print sprintf($fmt, ($m[$i] or $none), ($f[$i] or $none));
}
If you are interested in more sophisticated formatting (for instance center-aligned text), you should switch to the special formatting capabilities Perl provides for report generation.

Answer 5

Borrowing from #HunterMcMillen
use strict;
use warnings;
use feature "say";
local $, = "\t"; # separator when printing list
my $i = (#F_array > #M_array) ? $#F_array : $#M_array;
say qw(M F);
say $M_array[$i] //"", $F_array[$i] //"" for 0 .. $i;

Answer 6

I guess Text::Table is the required module which comes with the perl distribution(just need to install).Go through the below documentation -
Documentation of Text::Table
You need to pass the content as array to the add() method and it will do the wonders for you.