How to resolve this warning in Perl - perl

Question

I asked this type of ques previously but didn't provide the full code.
I am reading below file and checking the max word width present in each column and then write it to another file with proper alignment.
id0 id1 id2 batch
0 34 56 70
2 3647 58 72 566
4 39 616 75 98 78 78987 9876 7899 776
89 40 62 76
8 42 64 78
34 455 544 565
My code:
unlink "temp1.log";
use warnings;
use strict;
use feature 'say';
my $log1_file = "log1.log";
my $temp1 = "temp1.log";
open(IN1, "<$log1_file" ) or die "Could not open file $log1_file: $!";
my #col_lens;
while (my $line = <IN1>) {
my #fs = split " ", $line;
my #rows = #fs ;
#col_lens = map (length, #rows) if $.==1;
for my $col_idx (0..$#rows) {
my $col_len = length $rows[$col_idx];
if ($col_lens[$col_idx] < $col_len) {
$col_lens[$col_idx] = $col_len;
}
};
};
close IN1;
open(IN1, "<$log1_file" ) or die "Could not open file $log1_file: $!";
open(tempp1,"+>>$temp1") or die "Could not open file $temp1: $!";
while (my $line = <IN1>) {
my #fs = split " ", $line;
my #az;
for my $h (0..$#fs) {
my $len = length $fs[$h];
my $blk_len = $col_lens[$h]+1;
my $right = $blk_len - $len;
$az[$h] = (" ") . $fs[$h] . ( " " x $right );
}
say tempp1 (join "|",#az);
};
My warning
Use of uninitialized value in numeric lt (<) at new.pl line 25, <IN1> line 3.
Use of uninitialized value in numeric lt (<) at new.pl line 25, <IN1> line 4.
Use of uninitialized value in numeric lt (<) at new.pl line 25, <IN1> line 4.
Use of uninitialized value in numeric lt (<) at new.pl line 25, <IN1> line 4.
Use of uninitialized value in numeric lt (<) at new.pl line 25, <IN1> line 4.
Use of uninitialized value in numeric lt (<) at new.pl line 25, <IN1> line 4.
I am getting the output correctly but don't know how to remove this warnings.

Answer 1

$col_idx can be up to the number of fields on a line, minus one. For the third line, this is more than the highest index of #col_lens, which contains at most 3 elements. So doing the following makes no sense:
if ($col_lens[$col_idx] < $col_len) {
$col_lens[$col_idx] = $col_len;
}
Replace it with
if (!defined($col_lens[$col_idx]) || $col_lens[$col_idx] < $col_len) {
$col_lens[$col_idx] = $col_len;
}
With this, there's really no point checking for $. == 1 anymore.

Answer 2

You're getting uninitialized warning because, while checking the $col_lens[$col_idx] < $col_len condition, one or both of them are undef.
Solution 1:
You can skip checking this condition by the use of next statement.
for my $col_idx (0..$#rows) {
my $col_len = length $rows[$col_idx];
next unless $col_lens[$col_idx];
if ($col_lens[$col_idx] < $col_len) {
$col_lens[$col_idx] = $col_len;
}
}
Solution 2: (Not advised):
You can simply ignore Use of uninitialized value.. warnings by putting this line at top of your script. This will disable uninitialized warnings in a block.
no warnings 'uninitialized';
For more info, please refer this link

Answer 3

Following code demonstrates one of many possible ways for solution to this task
read line by line
get length of each field
compare with stored earlier
adjust to max length
form $format string for print
print formatted data
use strict;
use warnings;
use feature 'say';
my(#data,#length,$format);
while ( <DATA> ) {
my #e = split ' ';
my #l = map{ length } #e;
$length[$_] = ($length[$_] // 0) < $l[$_] ? $l[$_] : $length[$_] for 0..$#e;
push #data,\#e;
}
$format = join ' ', map{ '%'.$_.'s' } #length;
$format .= "\n";
for my $row ( #data ) {
printf $format, map { $row->[$_] // '' } 0..$#length;;
}
__DATA__
id0 id1 id2 batch
0 34 56 70
2 3647 58 72 566
4 39 616 75 98 78 78987 9876 7899 776
89 40 62 76
8 42 64 78
34 455 544 565
Output
id0 id1 id2 batch
0 34 56 70
2 3647 58 72 566
4 39 616 75 98 78 78987 9876 7899 776
89 40 62 76
8 42 64 78
34 455 544 565