CODEWITHSUNDEEP
rggplot2
Tiptop
Tiptop

Reputation: 623

Highlighting specific dates in a time series plotted in ggplot2

I need to visualize data from a weather station across ~3 months. During the season, gas sampling in the ground was performed on 5 specific dates. I would like to highlight these dates in the graph with weather station data.

I am trying to accomplish this by placing grey bars on the geom_point ggplot I have made

p <- ggplot(ws_may_sep_plot, aes (x = date_time, y = temperature)) +
geom_point(size=0.5) +
scale_x_datetime(breaks = "2 week")
ggtitle("Ambient temperature")

may_start <- "2012-05-22"
may_start_iso <- as.Date(may_start)

may_end <- "2012-05-23"
may_end_iso <- as.Date(may_start)

rect <- data.frame(xmin= may_start_iso, xmax= may_end_iso, ymin=-Inf, 
ymax=Inf)

p + geom_rect(data=rect, aes(xmin=xmin, xmax=xmax, ymin=ymin, ymax=ymax),
           color="grey20",
           alpha=0.5,
           inherit.aes = FALSE)

Here is a link to the data: https://www.dropbox.com/s/2z0branzp7r26gl/highlighting%20dates.R?dl=0

glimpse(ws_may_sep_plot)
Observations: 2,209
Variables: 8
Groups: rh, precipitation, temperature, par [2,203]
$ date_time <dttm> 2012-05-15 00:00:00, 2012-05-15 01:00:00, 2012-05-15 02:00:00, 2012-05-15 03:00:00, 201...
$ temperature <dbl> 3.1, 2.3, 3.3, 4.1, 5.1, 7.1, 8.1, 7.7, 8.0, 9.5, 11.0, 10.7, 9.9, 9.6, 9.6, 10.1, 9.9, ...

When I run my code I receive the following error:

Invalid input: time_trans works with objects of class POSIXct only

Upvotes: 1

Views: 919

Answers (1)

MDEWITT
MDEWITT

Reputation: 2368

USe scale_x_date("2 week") instead of scale_x_datetime. Your dates are only dates not datetimes (time component with date).


df <- data.frame(date = seq.Date(as.Date("2012-01-01"), as.Date("2012-07-01"), by = "day"),
                 temperature = rnorm(183, 30, 1))

p <- ggplot(df, aes (x = date, y = temperature)) +
  geom_point(size=0.5) +
  #scale_x_datetime(breaks = "2 week")
ggtitle("Ambient temperature")

may_start <- "2012-05-22"
may_start_iso <- as.Date(may_start)

may_end <- "2012-05-23"
may_end_iso <- as.Date(may_start)

rect <- data.frame(xmin= may_start_iso, xmax= may_end_iso, ymin=-Inf, 
                   ymax=Inf)

p + geom_rect(data=rect, aes(xmin=xmin, xmax=xmax, ymin=ymin, ymax=ymax),
              color="grey20",
              alpha=0.5,
              inherit.aes = FALSE)+
  scale_x_date(breaks = "2 week") # Should work!

Upvotes: 2

Related Questions