Reverse ggplot time scale

Question

I am creating a timetable plot to show how many events are in each time block. I have calculated all this information from lubridate and can plot it on ggplot fine. But I need to reverse/flip the axis so that the top shows 8am and goes down to 5pm rather than 5pm to 8am.

This is what a snippet of my end result currently looks like. Just need to reverse the time order and it will be perfect. This extends from 8am-5pm and M-F.

I tried using scale_y_reverse but this does not work.

I saw this post but I haven't been able to figure out how to use it for my situation: Reverse datetime (POSIXct data) axis in ggplot

Sample Data (created with dput fn):

df <- structure(list(ID = c(4108L, 4165L, 1504L, 2570L, 1523L, 2556L, 
3224L, 1503L, 3220L, 837L), START_TIME = structure(c(1504267200, 
1504281600, 1504258200, 1504278000, 1504263600, 1504256400, 1504258200, 
1504274400, 1504258200, 1504256400), class = c("POSIXct", "POSIXt"
), tzone = "UTC"), END_TIME = structure(c(1504270799, 1504285199, 
1504263599, 1504281599, 1504268999, 1504259999, 1504263599, 1504279799, 
1504263599, 1504259999), class = c("POSIXct", "POSIXt"), tzone = "UTC"), 
    Day = structure(c(5L, 5L, 2L, 3L, 2L, 3L, 4L, 2L, 4L, 1L), .Label = c("M", 
    "T", "W", "R", "F"), class = "factor")), row.names = c(322L, 
351L, 112L, 188L, 125L, 179L, 298L, 111L, 294L, 8L), class = "data.frame")

My Code:

library(ggplot2)
library(scales)

ggplot(df) +
    geom_rect(aes(xmin= 0, xmax= 2, ymin = START_TIME, ymax = END_TIME), 
              color = "#ffffff", 
              position="dodge") + 
    scale_y_datetime(date_breaks="1 hour", labels = date_format("%I:%M %p"), expand = expand_scale(.1)) + 
    theme_minimal() +
    theme(axis.ticks.x = element_blank(),
            axis.text.x = element_blank(),
            panel.grid = element_blank(),
            panel.grid.major.y = element_line(color = "#cccccc"),
            axis.title = element_blank()) +
    facet_wrap(~Day, nrow=1) 

Answer 1

I haven't been able to do this within the datetime scale, but one alternative is to convert to a numeric scale and handle the labeling manually:

library(lubridate)
df %>% 
  mutate(stime = hour(START_TIME) + minute(START_TIME)/60,
         etime = hour(END_TIME) + minute(END_TIME)/60) %>%

  ggplot() +
  geom_rect(aes(xmin= 0, xmax= 2, ymin = stime, ymax = etime), 
            color = "#ffffff", 
            position="dodge") + 
  scale_y_reverse(breaks = 6:23, 
                     labels = c(paste0(6:11, ":00 AM"), 
                                "12:00 PM",
                                paste0(1:11, ":00 PM")), 
                     expand = expand_scale(.1)) + 
  theme_minimal() +
  theme(axis.ticks.x = element_blank(),
        axis.text.x = element_blank(),
        panel.grid = element_blank(),
        panel.grid.major.y = element_line(color = "#cccccc"),
        axis.title = element_blank()) +
  facet_wrap(~Day, nrow=1)