Listen,
This is in the listview
Item Amount In/Out

Apple 10 in
Apple 5 out
Apple 3 in
Shoes 90 in
Shoes 5 out
Pants 23 in
Pants 44 in
Pants 9 out

This listview is filled from a text file which has nothing to do with my question

My question is with having
Apple 10 in
Apple 5 out
Apple 3 in
Shoes 90 in
Shoes 5 out
Pants 23 in
Pants 44 in
Pants 9 out

in a listview how can I clear this.
Then It makes from 2 or more the same item one and add or subtracts the amount depending if it went out or came in.

this way we can check how many item are currently in the depot

Thank you
Pieter