of-bound.R

# Create a bounding box
  # We want to slightly extend the edges so as to use all of our data
left <- ctd[ctd$date == min(ctd$date),] %>% 
  select(-temp) %>% 
  ungroup() %>% 
  mutate(date = date-0.01)
bottom <- ctd %>%
  group_by(date) %>% 
  summarise(depth = min(depth)) %>% 
  mutate(depth = depth-0.01)
right <- ctd[ctd$date == max(ctd$date),] %>% 
  select(-temp) %>% 
  ungroup() %>% 
  mutate(date = date+0.01)
top <- ctd %>%
  group_by(date) %>% 
  summarise(depth = max(depth)) %>% 
  mutate(depth = depth+0.01)
bounding_box <- rbind(data.frame(left[order(nrow(left):1),]), data.frame(bottom), 
                      data.frame(right), data.frame(top[order(nrow(top):1),]))

# Now that we have a bounding box we need to 
# screen out the pixels created outside of it
bounding_box_list <- list(bounding_box)
names(bounding_box_list[[1]]) <- c("v","w")
v <- ctd_mba$date
w <- ctd_mba$depth
ctd_mba_bound <- ctd_mba[inSide(bounding_box_list, v, w),]

# The screened data
ggplot(data = ctd_mba_bound, aes(x = date, y = depth)) +
  geom_raster(aes(fill = temp)) +
  scale_fill_gradientn(colours = rev(ODV_colours)) +
  geom_contour(aes(z = temp), binwidth = 2, colour = "black", alpha = 0.2) +
  geom_contour(aes(z = temp), breaks = 20, colour = "black") +
  labs(y = "depth (m)", x = NULL, fill = "temp. (°C)") +
  coord_cartesian(expand = 0)