Using

CodePudding user response：

The segment simply has the co-ordinates you gave it. A vertical line would be something like this:

kncoast <- data.frame(orig_lat=12.7571, 
                      orig_lon=74.87461,
                      dest_lat=15,
                      dest_lon=74.87461) 

If you want the line to stretch across the coast of Karnataka, then something like this would be better:

kncoast <- data.frame(orig_lat=12.7571, 
                      orig_lon=74.87461,
                      dest_lat=14.75,
                      dest_lon=74.15)