How to simplify a polyline in grasshopper?

I have a quadrilateral,but there are five line.So that means there are two lines in one direction.I want to simplify them then get the short lines center point.But now there are five lines,I don’t know how to do it.How to transfrom the lines which in the same direction to one line(in grasshopper)?

Simplify curve might help you, although I guess it depends on your seam location, if it is at the start and end, this component might not be able to help.