I've used the splice solution, but it offended me that you have to copy the array just to destroy it. I came up with a version of my mapn function that avoids the splice (and therefore the need to copy as well), by using slices and a pointer.

There are two versions of the function mapn and mapnz. With the former, number of values produced in the last row is just how ever many are left over.

With the latter, it pads (with nulls, hence the 'z') the last list of returned values to be the same size as the rest of the rows. This can be useful for things like tables, where although most browsers will tolorate there being less <td></td> pairs in the last row, they do not render this very well. By using mapnz in conjunction with an 8-char patch I made to CGI.pm so that empty TD's have a &nbsp; inserted, forces most browsers to render the borders around missing values.

#! perl -slw
use strict;
use CGI qw[td Tr :table caption];

sub mapn (&@) {
    my($c, $n, $s) = (shift, shift, 0);
    map{
        $s+=$n; $c->( @_[($s-$n) .. ($s < @_ ? $s-1 : @_-1) ] );
    } 0 .. (@_/$n);
}

sub mapnz (&@) {
    my($c, $n, $s) = (shift, shift, 0);
    map{
        $s+=$n; $c->( @_[($s-$n) .. ($s - 1) ] );
    } 0 .. (@_/$n);
}

my @tabular_data = map{ 1000+int rand 8999 } 1 .. 31;

print
    table( {border=>1}, $/,
        mapn{ Tr( td( \@_ ) ).$/; } 5, @tabular_data
    );

print
    table( {border=>1}, $/,
        caption('Columns: ' . $_), $/,
        mapnz{ Tr( td( \@_ ) ).$/ } $_, @tabular_data
    ) for 3 .. 8;

__END__
C:\test>236799
<table border="1">
 <tr><td>4978</td> <td>7782</td> <td>3230</td> <td>3524</td> <td>7570<
+/td></tr>
 <tr><td>9627</td> <td>4424</td> <td>7968</td> <td>2523</td> <td>1838<
+/td></tr>
 <tr><td>9843</td> <td>8797</td> <td>5034</td> <td>8499</td> <td>3683<
+/td></tr>
 <tr><td>5591</td> <td>2402</td> <td>6131</td> <td>2649</td> <td>5917<
+/td></tr>
 <tr><td>1333</td> <td>7874</td> <td>7031</td> <td>2269</td> <td>3766<
+/td></tr>
 <tr><td>2151</td> <td>1350</td> <td>7235</td> <td>5986</td> <td>1447<
+/td></tr>
 <tr><td>2627</td></tr>
</table>
<table border="1">
 <caption>Columns: 3</caption>
 <tr><td>4978</td> <td>7782</td> <td>3230</td></tr>
 <tr><td>3524</td> <td>7570</td> <td>9627</td></tr>
 <tr><td>4424</td> <td>7968</td> <td>2523</td></tr>
 <tr><td>1838</td> <td>9843</td> <td>8797</td></tr>
 <tr><td>5034</td> <td>8499</td> <td>3683</td></tr>
 <tr><td>5591</td> <td>2402</td> <td>6131</td></tr>
 <tr><td>2649</td> <td>5917</td> <td>1333</td></tr>
 <tr><td>7874</td> <td>7031</td> <td>2269</td></tr>
 <tr><td>3766</td> <td>2151</td> <td>1350</td></tr>
 <tr><td>7235</td> <td>5986</td> <td>1447</td></tr>
 <tr><td>2627</td> <td>&nbsp;</td> <td>&nbsp;</td></tr>
</table>
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