geom_segment(mapping = NULL, data = NULL,
stat = "identity", position = "identity", arrow = NULL,
lineend = "butt", na.rm = FALSE, ...)aes or aes_string. Only
needs to be set at the layer level if you are overriding
the plot defaults.FALSE (the default), removes
missing values with a warning. If TRUE silently
removes missing values.geom_segment