in the ggplot2 plot of time series, generate vertical red lines at each date indicated in the "date" column of another dataframe in r

One way to generate vertical red lines on a ggplot2 time series plot at each date indicated in the "date" column of another dataframe is by using the geom_vline function.

Here is some sample code that demonstrates this approach:

main.r
library(ggplot2)

# create sample time series data
set.seed(123)
dates <- seq(as.Date("2000/1/1"), by = "month", length.out = 48)
values <- cumsum(rnorm(48))
df <- data.frame(date = dates, value = values)

# create sample dataframe of red line dates
red_dates <- data.frame(date = c(as.Date("2001/1/1"), as.Date("2002/1/1"), as.Date("2003/1/1")))

# plot time series with red lines
ggplot(df, aes(x = date, y = value)) +
  geom_line() +
  geom_vline(data = red_dates, aes(xintercept = date), color = "red")
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In this example, we first create a sample time series dataset df with two columns: "date" and "value". We then create a separate dataframe red_dates with a single column "date" indicating the dates for which we want to add the red lines to the plot.

To add the red lines to the plot, we use geom_vline and specify the data argument as red_dates to indicate that we want to use the dates in this dataframe for the vertical lines. We also use aes(xintercept = date) to specify that the date column in red_dates should be used to determine the location of the vertical lines. Finally, we set the color argument to "red" to indicate that we want the lines to be red.

This code will generate a plot of the time series with vertical red lines at each date indicated in the red_dates dataframe.