Cutting lots of polylines using single horizontal line in ArcGIS for Desktop?

Question

I have 2000 polylines or more, each polyline have about 2000-3000 vertices. I want cut all part of polylines that are below a single horizontal line. How can I do that in Arcgis?

I try to use intersect tool: polylines layer with the layer horizontal line (with output "point"). In this way I obtain points intersection, I can use it to split the polylines and finally I can delete all polylines below the horizontal line by simply selection the area. The problem is that the first step, intersecate polylines with the single horizontal line, take an infinte process. My idea isn't good, is there another fast solution?

Answer 1

• Extend your Split (single) line to the West, beyond left most line
• Extend your Split (single) line to the East, beyond right most line

The next two steps are for lazy person and keeping programming in mind:

arcpy.MinimumBoundingGeometry_management("Many Lines","D:/Scratch/rectangle.shp", "RECTANGLE_BY_AREA", group_option="ALL")
arcpy.FeatureToPolygon_management(in_features="rectangle;'Single Line'", "D:/Scratch/splitRectangle.shp")

OUTPUT CONTAINS 2 POLYGONS:

Select lower polygon and use it for Erase tool with lines to be split, alternatively select upper one and use it for Clip tool.