Plot two variables as lines on the same graph using ggplot

Question

Consider a data like this:

data <-
  data.frame(
    variable0 = 100 + c(0, cumsum(runif(49, -20, 20))),
    variable1 = 150 + c(0, cumsum(runif(49, -10, 10))),
    date = seq(as.Date("2007-01-01"), by="1 month", length.out=100)
  )

How to plot time series for variable0 and variable1 on the same graph with date on x-axis.

I want to use ggplot2.

Can someone please help?

Answer 1

If you have small number of variables, then you use build the plot manually

ggplot(data, aes(date)) + 
  geom_line(aes(y = variable0, colour = "variable0")) + 
  geom_line(aes(y = variable1, colour = "variable1"))