foreach my $k (keys %hash){
    $hash{$k} =~ s/,(?! )/, /g;
  }

[download]
Update: $hash{$_} =~ s/,(?! )/, /g for keys %hash;
Update: Taking it even one more step is tedpride's nice solution below, avoiding keys altogether.

In reply to Re: regex to break on commas by davidrw
in thread regex to break on commas by Anonymous Monk

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