"Cave plot" proof of concept

caveplot.R

library(dplyr)

df_north <- tibble(
  week = 1:53,
  N = sample(0:15, 53, replace = T)
)


df_south <- tibble(
  week = 1:53,
  N = sample(0:15, 53, replace = T)
)


library(ggplot2)

# Method 1: one plot
ggplot() +
  geom_col(data = df_north, aes(x = week, y = -N),
           # Need to nudge by at least twice the maximum value
           position = position_nudge(y = 30)) +
  geom_col(data = df_south, aes(x = week, y = N)) +
  scale_x_continuous(breaks = round(seq(1, 53, length.out = 12)),
                     labels = month.abb) +
  # Correct the y axis labels
  scale_y_continuous(breaks = seq(0, 30, 5), labels = c(0, 5, 10, 15, 10, 5, 0)) +
  labs(title = 'Method 1')


# Method 2: two plots combined, correct y axis
library(patchwork)

north <- ggplot() +
  geom_col(data = df_north, aes(x = week, y = N)) +
  scale_y_reverse() +
  scale_x_continuous(breaks = round(seq(1, 53, length.out = 12))) +
  theme(axis.text.x = element_blank(),
        axis.title.x = element_blank(),
        plot.margin = margin(0,0,0,0))

south <- ggplot() +
  geom_col(data = df_south, aes(x = week, y = N)) +
  scale_x_continuous(breaks = round(seq(1, 53, length.out = 12)),
                     labels = month.abb) +
  theme(plot.margin = margin(0,0,0,0))

north / south + plot_annotation(title = 'Method 2')