plotting Date ranges for each ID and marking specific Dates using ggplot

Question

Here is my data


mydata = data.frame (id =c(1,1,2,3,3,4,4,5,6,6,7,7,8),
                     startdate=c("2014-01-21","2015-04-01","2016-03-15","2013-01-13","2014-01-02","2017-04-05","2021-07-22","2022-03-01","2016-01-28","2016-05-05",
                                 "2015-04-16","2015-09-01","2019-01-24"),
                     enddate = c("2015-03-06","2016-01-01","2017-04-01","2013-11-11", "2014-05-06","2018-12-24","2022-02-02","2022-05-02","2016-04-07","2016-07-12","2016-02-02",
                                 "2018-08-23","2019-03-15"),
                     dx_date = c("2014-03-03","2014-03-04","2016-05-05","2013-04-04","2013-04-04","2017-06-06","2021-12-25","2021-12-25","2016-03-08",
                                 "2016-03-08","2015-07-07","2016-11-12","2016-11-12"))

I would like to plot out the time between start and end date for each ID, which I have done below.

ggplot(mydata) + 
  geom_linerange(aes(y = id, xmin = startdate, xmax = enddate ), size = 4,
                 color = "orange") +
  xlab("date")

Which gives me the following:

However now i m trying to mark (with maybe a star or a vertical line across the bar) the dx_date for each id on the graph as well,and Im not entirely sure how to do about doing this. Im looking to do something like the below (just drew it in) using the dx_date. Any help would be greatly appreciated!!

If you add geom_point(aes(y = id, x = dx_date), shape = 18) will that give you what you are looking for? — Ben
Your "dates" are strings, not dates. Have you use as.Date or as.POSIXct to convert them from a categorical string to a number-like date object? — r2evans

r2evans r2evans · Accepted Answer · 2022-05-09T01:41:55

You should use Date objects instead of strings: it makes the x-axis a lot easier to read, better shows gaps and relative time gaps, and allows many other controls over the aesthetics.

As for the additional dots, just add another geom_point. You can control the dates on the x-axis using scale_x_date, which I'll demo in the code below; it's use is not required, and in this case it would show every other year on the x-axis.

mydata[c("startdate","enddate","dx_date")] <- lapply(mydata[c("startdate","enddate","dx_date")], as.Date)
ggplot(mydata, aes(y=id)) +
  geom_linerange(aes(xmin=startdate, xmax=enddate), size=4, color = "orange") +
  geom_point(aes(x=dx_date)) +
  scale_x_date(date_breaks = "1 year", date_labels = "%Y-%m")

plotting Date ranges for each ID and marking specific Dates using ggplot

1 Answers