ggplot2中的自定义日期轴

Question

I am trying to generate a plot in ggplot2 with customized ticks. The problem is if I choose eg date_breaks = "5 years" , the plot will start the labeling at the very last date year, and go back in 5 year intervals, but miss on the first date. This makes sense, but what if I would like to show the first date as well so people see the beginning of my plot? Moreover, the ticks in between are not shown. So what I would like to have is:

• 5 year intervals, each labelled (eg assume a label at 1988) and also marked on the axis
• 1 year marks not labelled in between (eg if we assume 1988 is labelled, 1989 to 1992 should only be marked on the axis with ticks, but not be labelled)
• a custom start date for the labeling and a custom end date for the labeling. Now of course both is likely not possible if numbers are not in the sequence of 5 years. In this case, it probably makes sense to decide for either a custom start/end date and do the labeling from there. Let me know what you think is the best solution in this case.

MWE:

set.seed(1)
test <- data.table(x = rnorm(29*2),var=c(rep("x1",29),rep("x2",29)),
                   time=rep(seq(as.Date("1983/12/31"),as.Date("2011/12/31"), "year"),2))
library(ggplot2);library(scales)
ggplot(data=test,aes(x=time, y=x, colour=var)) + 
geom_line() + scale_x_date(date_labels="%Y",date_breaks = "5 years",
                             date_minor_breaks="1 year")

Answer 1

You could just define breaks and labels manually which you can adjust arbitrarily.

dts <- as.Date(paste0(seq(1980, 2015, 1), "-01-01"))
x.labs <- substr(as.character(dts), 1, 4)
x.labs[5:length(dts - 2) %% 5 != 0] <- ""  # modulo 5

library(ggplot2);library(scales)
ggplot(data=test, aes(x=time, y=x, colour=var)) + 
  geom_line() + 
  scale_x_date(breaks=dts, labels=x.labs)

Yielding