Can you explain what Path Mappers does in this case?

I am analysing this grasshopper model, with which a tall building in the shape of a Diagrid is realised. Once the diagonals have been identified, the ‘Path Mapper’ command is used and then connected to the Line input of the Line To Beam component. Then, again using the ‘Path Mapper’ component, it is linked to the BeamId input of the Line To Beam component. Can you explain to me in essence what this component used twice allows me to do in these cases?
Modello finale (186.5 KB)

Your script shows something totally different.
The pathmapper allows you to control the structure of your data by manipulating the branches and items.