Directly Plotting ts object with ggplot2

Question

I wonder if there is a function to plot ts object directly with ggplot2. In past, I was using the following strategy but now it is throwing an error.

set.seed(12345)
dat <- ts(data=runif(n=10, min=50, max=100), frequency = 4, start = c(1959, 2))
df <- data.frame(date=as.Date(time(dat)), Y=as.matrix(dat))
library(ggplot2)
ggplot(data=df, mapping=aes(x=date, y=Y))+geom_point()

Error

Error in as.Date.default(time(dat)) : 
  do not know how to convert 'time(dat)' to class “Date”

How can I directly plot ts object with ggplot2.

Answer 1

Try this:

library(zoo)
library(ggplot2)
library(scales)

autoplot(as.zoo(dat), geom = "point")

or maybe:

autoplot(as.zoo(dat), geom = "point") + scale_x_yearqtr()

See ?autoplot.zoo for more info.

Note: The code in the question works if you issue the command library(zoo) first.

Updates Added second solution, library(scales) and switched from yearmon to yearqtr.

Answer 2

Don't know why it worked before (since it would not seem to be valid under my understanding of Date functins) but you can fix it with the use of zoo::as.yearqtr

library(zoo)
?as.yearqtr
set.seed(12345)
dat <- ts(data=runif(n=10, min=50, max=100), frequency = 4, start = c(1959, 2))
df <- data.frame(date=as.Date(as.yearqtr(time(dat))), Y=as.matrix(dat))
library(ggplot2)
ggplot(data=df, mapping=aes(x=date, y=Y))+geom_point()
# No errors. The plot has YYYY-MM labeling as expected for a ggplot2-Date axis.

Answer 3

This code works for me

set.seed(12345)
dat <- ts(data=runif(n=10, min=50, max=100), frequency = 4, start = c(1959, 2))
library(ggfortify)
autoplot(dat, geom = "point", ts.colour = ('dodgerblue3')) #Option 1

library(zoo)
autoplot.zoo(as.zoo(dat), geom = "point") #Option 2