The general approach is to convert the data to long format (using melt()
from package reshape
or reshape2
) or gather()
/pivot_longer()
from the tidyr
package:
library("reshape2")
library("ggplot2")
test_data_long <- melt(test_data, id="date") # convert to long format
ggplot(data=test_data_long,
aes(x=date, y=value, colour=variable)) +
geom_line()
Also see this question on reshaping data from wide to long.