Lets say I have the following dataset:

dt <- data.frame(id= c(1),
                 parameter= c("a","b","c"),
                 start_day = c(1,8,4),
                 end_day = c(16,NA,30))

I want to create a type of line chart such that "parameter" column is my y-axis and both ("start_day" and "end_day") are on my x-axis.

Alo, if both "start_day" and "end_day" have values, then they be connected through a line. In case there is no "end_day" (like for parameter "b") then the "start_day" be connected to an arrow indicating there is no "end_day" for that parameter. (I know it sound confusing but I will make an example to clarify)

I know that for

What I am looking for at this point is to find a way to draw a line between "start_day" and "end_day" (given both end and start day exist). And if there is no "end_day" I want an arrow indicates that there is no end date (the exact opposite of what I am getting right now).

Any help is much appreciated.

CodePudding user response：

To draw a line between points where the values are in separate columns you could use geom_segment. To add an arrow to obs with no end date one option would be to split your data into two parts, one with non-missing and one with missing end-dates, and use two geom_segments:

library(ggplot2)

ggplot(dt, aes(y = parameter))   
  geom_segment(data = ~subset(.x, !is.na(end_day)), aes(x = start_day, xend = end_day, yend = parameter))  
  geom_segment(data = ~subset(.x, is.na(end_day)), aes(x = start_day, xend = start_day   1, yend = parameter), 
               arrow = arrow(type = "closed", length = unit(0.1, "inches")))  
  geom_point(aes(x = start_day, shape = "start_day"), size = 3, color = "red")  
  geom_point(aes(x = end_day, shape = "end_day"), size = 3, color = "red")  
  scale_shape_manual(values = c(16, 17))
#> Warning: Removed 1 rows containing missing values (geom_point).