About interval selection

Hello everyone,
As shown in the arrow below.
I originally planned to take lines at intervals, but I don’t know why I got these complete lines
Does anyone know how to modify it, thanks.

data1.gh (19.6 KB)

The problem is that you have a long line from LastPoint to FirstPoint:

You can get rid of this line by Inverting Wrap input of ShiftList:

1 Like

thanks :joy:

A cleaner approach:

IntervalSelection.gh (25.6 KB)