ggplot overlay is overwriting my x axis timeline, how to prevent? - r

Question

I have a ggplot which is doing exactly as I want till I add an overlay to it. The data to replicate are below, here's the ggplot:
timeline <- ggplot(dataset, aes(x = Month, y = Sessions,fill = Channel, group = Channel)) +
geom_area(alpha = 0.3) +
stat_summary(aes(group = 2), fun.y = sum, geom = 'line', size = 2, alpha = 0.5) +
theme(axis.text.x=element_text(angle=90, hjust=1),
axis.title.x = element_blank())
Results:
So far so good. Note the x-axis showing months in order. Then I add an overlay (see example data below to generate the variables in the code):
# make overlay representing TV
tv_begin <- sample(mts, 4)
tv_end <- tv_begin %m+% months(1)
tv_overlay <- data.frame(start = format(tv_begin, "%b-%Y"), end = format(tv_end, "%b-%Y"))
Then:
timeline + geom_rect(data = tv_overlay, inherit.aes = FALSE,
aes(xmin = start, xmax = end,
ymin = -Inf, ymax = Inf,
alpha = "TV On"),
fill = "black")
Results:
Now my x axis months are not ordered and I don't know how to prevent this happening? How can I maintain the x axis OR how can I have the new overlay inherit from them so that adding the overlay does not change the x-axis?
----Here's the data to replicate variable "dataset"-----
## Build dummy data
library(dplyr)
# dimensions
channels <- c("Facebook", "Youtube", "SEM", "Organic", "Direct", "Email")
last_month <- Sys.Date() %m+% months(-1) %>% floor_date("month")
mts <- seq(from = last_month %m+% months(-23), to = last_month, by = "1 month")
yr_month <- format(mts, "%b-%Y")
dimvars <- expand.grid(Month = yr_month, Channel = channels)
# metrics
rws <- nrow(dimvars)
set.seed(42)
# generates variablility in the random data
randwalk <- function(initial_val, ...){
initial_val + cumsum(rnorm(...))
}
Sessions <- ceiling(randwalk(3000, n = rws, mean = 8, sd = 1500)) %>% abs()
Transactions <- ceiling(randwalk(200, n = rws, mean = 0, sd = 75)) %>% abs()
Revenue <- ceiling(randwalk(10000, n = rws, mean = 0, sd = 3500)) %>% abs()
Spend <- ceiling(randwalk(6000, n = rws, mean = 0, sd = 3500)) %>% abs()
# make primary df
dataset <- cbind(dimvars, Sessions, Transactions, Revenue, Spend) %>%
mutate(Spend = ifelse(Channel %in% c("Direct", "Organic"), NA, Spend))

Answer 1

Remove the format() calls from your code. It turns everything to strings/factors.
Here I have converted x-axis data with as.Date(), and formatted the x-Axis in the plot with scale_x_date():
library(tidyverse)
library(lubridate)
# dimensions
channels <- c("Facebook", "Youtube", "SEM", "Organic", "Direct", "Email")
last_month <- Sys.Date() %m+% months(-1) %>% floor_date("month") %>% as.Date()
mts <- seq(from = last_month %m+% months(-23), to = last_month, by = "1 month") %>% as.Date()
#yr_month <- format(mts, "%b-%Y")
yr_month <- mts # format(mts, "%b-%Y")
dimvars <- expand.grid(Month = yr_month, Channel = channels, stringsAsFactors = FALSE)
rws <- nrow(dimvars)
set.seed(42)
# generates variablility in the random data
randwalk <- function(initial_val, ...){
initial_val + cumsum(rnorm(...))
}
Sessions <- ceiling(randwalk(3000, n = rws, mean = 8, sd = 1500)) %>% abs()
Transactions <- ceiling(randwalk(200, n = rws, mean = 0, sd = 75)) %>% abs()
Revenue <- ceiling(randwalk(10000, n = rws, mean = 0, sd = 3500)) %>% abs()
Spend <- ceiling(randwalk(6000, n = rws, mean = 0, sd = 3500)) %>% abs()
# make primary df
dataset <- cbind(dimvars, Sessions, Transactions, Revenue, Spend) %>%
mutate(Spend = ifelse(Channel %in% c("Direct", "Organic"), NA, Spend))
glimpse(dataset)
# make overlay representing TV
tv_begin <- sample(mts, 4)
tv_end <- tv_begin %m+% months(1)
tv_overlay <- data.frame(start = tv_begin, end = tv_end)
glimpse(tv_overlay)
timeline <- ggplot(dataset, aes(x = Month, y = Sessions,fill = Channel, group = Channel)) +
geom_area(alpha = 0.3) +
stat_summary(aes(group = 2), fun.y = sum, geom = 'line', size = 2, alpha = 0.5) +
theme(axis.text.x=element_text(angle=90, hjust=1),
axis.title.x = element_blank()) +
scale_x_date(date_labels = "%b-%d", date_breaks = "1 month")
timeline + geom_rect(data = tv_overlay, inherit.aes = FALSE,
aes(xmin = start, xmax = end,
ymin = -Inf, ymax = Inf,
alpha = "TV On"),
fill = "black")