grep{$_} .......

##</code><code>##

grep{defined $_} .....

##</code><code>##

@array -1

##</code><code>##

$#array

##</code><code>##

map{[
   grep {defined}
   @array[$_*$len..$_*$len+$len-1]
   ]} 0..$#array/$len