in reply to Re^10: constructing a tree from csv file
in thread constructing a tree from csv file

Use a condition:
print " , ", $path_string, ', ', $group{$path_string} if exists $group +{$path_string};
لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ