How to have changing x-axis intervals in one Graph using Date? (ggplot)

Question

I am trying to plot a time series using ggplot. I have aggregated monthly and weekly data for the last couple of years. I want my plot to show monthly data for five years until a certain cut-off. After this cut-off I want to show weekly data for one year. However, I want those two parts to be off the same horizontal length so that the weekly data can be seen in more detail. Is there a way to scale the x axis manually so that half of it covers a five-year period and the other half of it covers the adjacent one-year period?

I have tried to find an answer for a long-period of time and would be very grateful if somebody had an idea how to solve this.

Answer 1

Difficult to tell without a reproducible example, but it sounds like your data are probably something like this:

library(ggplot2)

set.seed(69)

df <- data.frame(dates = c(seq(as.POSIXct("2014-01-01"), 
                               as.POSIXct("2018-12-01"), by = "1 month"),
                           seq(as.POSIXct("2019-01-01"), by = "1 week",
                               length.out = 52)),
                 values = (cumsum(runif(112, -0.4, 0.6)) + 10) * 1000)

ggplot(df, aes(dates, values)) + geom_line()

If you want your plot split into two panels, the easiest way to achieve this is to create a new column that denotes which panel you want each row to be in;

df$Period = as.factor(df$date > as.POSIXct("2019-01-01"))
levels(df$Period) <- c("Monthly (pre 2019)", "Weekly (2019")

Now you can just plot with facet_grid according to your new factor:

ggplot(df, aes(dates, values)) + 
  geom_line() + 
  facet_grid(.~Period, scales = "free_x")

^{Created on 2020-07-15 by the reprex package (v0.3.0)}