(updated) I have ggplot like this, but then the x axis Date scaled:
g1 <- ggplot(diamonds, aes(clarity, fill=cut)) + geom_bar()
Above two bars (lets say VS2 and IF, but in my graph it is a date) I want to put a text label above the bars at height 13.000.
I tried a lot of things, but this is what came closest:
This is what I tried in my graph with the Date axis
g1 + geom_text(aes(as.Date("2014-10-05"), 13000), label="boat")
but this adds only one to the graph and as soon as I try to extend it, for example with
g1 + geom_text(aes(c(as.Date("2014-10-05"),as.Date("2014-10-20")) , 13000), label=c("boat", "train"))
then I get the error:
Error: Aesthetics must either be length one, or the same length as the dataProblems:c(as.Date("2014-10-05"), as.Date("2014-10-20"))
I also tried to read the text and labels from a dataframe (oefen), where I used the same names as the original plot
g1 + geom_text(data=oefen, aes(x=newdat, y=Number, label=oefen$labs, fill=1))
I get the error
Error: Continuous value supplied to discrete scale
I tried many other solutions, but cannot find the answer. What am I missing?
Answer
Consider using annotate() to place whatever text where you want at a given location on the plot. Factor variables, as in the clarity factor on the x-axis, have a number for each level, so you can use that number to locate the text. I assume date variables have the same usage.:
ggplot(diamonds, aes(clarity, fill=cut)) + geom_bar() +
annotate("text", x=8, y=13000, label= "boat") +
annotate("text", x = 4, y=13000, label = "ship")
EDIT after COMMENT
For efficiency, you can combine the annotations, such as this:
ggplot(diamonds, aes(clarity, fill=cut)) + geom_bar() +
annotate("text", x = c(2,4,6,8), y=13000, label = c("two", "ship", "six", "boat"))