This site loves to explain code .. so keep those questions coming.
@$r is the same as @{ $r } .
$r is an array-reference ... adding the @{ } around it converts that into an array that can be iterated.
'map' will "transform" each element of the array, returning a modified array.
The "transformation" is in the form of a regular-expression - in this case, it extracts "word" type characters (\w), decimals (.) and so on. See perlre.
The result of this map is stored in the array @cols, which is later printed.
Hope this helps. If still unclear .. experiment, and come back with more specific questions.
...it is unhealthy to remain near things that are in the process of blowing up. man page for WARP, by Larry Wall
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