how to output data from multiple files in side by side columns in one file via awk?

I have 30 files, called UE1.dat, UE2.dat .... with 4 columns in every of them. An example of their column structure is given below for UE1.dat and UE2.dat.

UE1.dat

1 4 2 1 
2 2 3 3
3 2 4 4   
4 4 4 2

UE2.dat

2 6 8 7 
4 4 9 6
7 1 1 2   
9 3 3 3

So, i have tried with the following code:

for((i=1;i<=30;i++)); do awk 'NR$i {printf $1",";next} 1; END {print ""}' UE$i.dat; done > UE_all.dat

to get only the first column from every file and write them in a single file and columns to be side by side,The desired OUTPUT is given below.

1 2
2 4
3 7
4 9

But unfortunately, the code orders them in rows, can you give a hint?

Thank you in advance!

I'd probably go with something like - using perl rather than awk because I prefer the handling of data structures. In this case - we use a two dimensional array, insert the first column of each file into a new column of the array, then print the whole thing.

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

my $num_files = 2; 

my @rows;
my $count = 0; 
my $max = 0; 

for my $filenum ( 1..$num_files ) {
    open ( my $input, "<", "UE${filenum}.dat" ) or die $!;
    while ( <$input> ) {
        my @fields = split;
        push ( @{$rows[$filenum]}, $fields[0] );
        $count++;
    } 
    close ( $input ); 
    if ( $count > $max ) { $max = $count };
}

print Dumper \@rows;

for ( 0..$count ) { 
    foreach my $filenum ( 1..$num_files ) {
       print shift @{$rows[$filenum]} || ''," ";
    }
    print "\n";
}