How to get a vertical geom_vline to an x-axis of class date?

Question

Even though I found Hadley's post in the google group on POSIXct and geom_vline, I could not get it done. I have a time series from and would like to draw a vertical line for years 1998, 2005 and 2010 for example. I tried with ggplot and qplot syntax, but still I either see no vertical line at all or the vertical line is drawn at the very first vertical grid and the whole series is shifted somewhat strangely to the right.

gg <- ggplot(data=mydata,aes(y=somevalues,x=datefield,color=category)) +
      layer(geom="line")
gg + geom_vline(xintercept=mydata$datefield[120],linetype=4)
# returns just the time series plot I had before, 
# interestingly the legend contains dotted vertical lines

My date field has format "1993-07-01" and is of class Date.

Can you add a few rows of your dataframe, so that we can try your example? — Sarah West, Mar 22 '11 at 12:52

rcs · Accepted Answer · 2020-04-13T14:36:07.437

167

Try as.numeric(mydata$datefield[120]):

gg + geom_vline(xintercept=as.numeric(mydata$datefield[120]), linetype=4)

A simple test example:

library("ggplot2")

tmp <- data.frame(x=rep(seq(as.Date(0, origin="1970-01-01"),
                            length=36, by="1 month"), 2),
                  y=rnorm(72),
                  category=gl(2,36))

p <- ggplot(tmp, aes(x, y, colour=category)) +
     geom_line() +
     geom_vline(xintercept=as.numeric(tmp$x[c(13, 24)]),
                linetype=4, colour="black")
print(p)

geom_vline example plot

edited Apr 13 '20 at 14:36

answered Mar 22 '11 at 13:15

rcs

67,191
22
172
153

I found the 'as.numeric()' actually quite hard to find! Thanks. – arno_v Oct 01 '13 at 19:56
3

I wonder if `geom_vline(aes(xintercept=as.numeric(x[c(13, 24)])), linetype=4, colour="black")` would be more idiomatic, i.e., using `aes` instead of `tmp$`. – David Arenburg Jan 21 '15 at 14:36
1

This solution no longer works. Code produces ```Error: Attempted to create layer with no stat. Run `rlang::last_error()` to see where the error occurred.``' – CoderGuy123 Apr 12 '20 at 23:57

score 57 · Answer 2 · answered Feb 14 '17 at 23:07

57

You could also do geom_vline(xintercept = as.numeric(as.Date("2015-01-01")), linetype=4) if you want the line to stay in place whether or not your date is in the 120th row.

answered Feb 14 '17 at 23:07

D.Hadley

1,179
13
13

23

on my machine (Win10 with R 3.2.2 and ggplot 1.0.1), I have to coerce the date to POSIXct to get it to align properly: `as.POSIXct(as.Date(c("2016-12-01","2017-02-01")))` – Jthorpe Jul 28 '17 at 17:36
1

Thank you Jthorpe.. this is the only version that worked for me – ColorStatistics May 22 '20 at 12:44

score 6 · Answer 3 · answered Nov 26 '20 at 09:06

Depending on how you pass your "Dates" column to aes, either as.numeric or as.POSIXct works:

library(ggplot2)

using aes(as.Date(Dates),...)

ggplot(df, aes(as.Date(Dates), value)) +
   geom_line() +
   geom_vline(xintercept = as.numeric(as.Date("2020-11-20")), 
              color = "red", 
              lwd = 2)

using aes(Dates, ...)

ggplot(df, aes(Dates, value)) +
   geom_line() +
   geom_vline(xintercept = as.POSIXct(as.Date("2020-11-20")), 
              color = "red", 
              lwd = 2)

score 4 · Answer 4 · edited Apr 23 '22 at 17:05

as.numeric works to me

ggplot(data=bmelt)+
  geom_line(aes(x=day,y=value,colour=type),size=0.9)+
  scale_color_manual(labels = c("Observed","Counterfactual"),values = c("1","2"))+
  geom_ribbon(data=ita3,aes(x=day, 
      y=expcumresponse, ymin=exp.cr.ll,ymax=exp.cr.uu),alpha=0.2) +
  labs(title="Italy Confirmed cases",
        y ="# Cases ", x = "Date",color="Output")+
  geom_vline(xintercept = as.numeric(ymd("2020-03-13")), linetype="dashed", 
                color = "blue", size=1.5)+
  theme_minimal()

How to get a vertical geom_vline to an x-axis of class date?

4 Answers4

Linked

Related