R ggplot2 position_stack 將重疊的對象堆疊在一起

position_stack(vjust = 1, reverse = FALSE)

position_fill(vjust = 1, reverse = FALSE)

有關更多示例，請參閱geom_bar() 和 geom_area()。

其他位置調整：position_dodge()、position_identity()、position_jitterdodge()、position_jitter()、position_nudge()

# Stacking and filling ------------------------------------------------------

# Stacking is the default behaviour for most area plots.
# Fill makes it easier to compare proportions
ggplot(mtcars, aes(factor(cyl), fill = factor(vs))) +
  geom_bar()

ggplot(mtcars, aes(factor(cyl), fill = factor(vs))) +
  geom_bar(position = "fill")


ggplot(diamonds, aes(price, fill = cut)) +
  geom_histogram(binwidth = 500)

ggplot(diamonds, aes(price, fill = cut)) +
  geom_histogram(binwidth = 500, position = "fill")


# Stacking is also useful for time series
set.seed(1)
series <- data.frame(
  time = c(rep(1, 4),rep(2, 4), rep(3, 4), rep(4, 4)),
  type = rep(c('a', 'b', 'c', 'd'), 4),
  value = rpois(16, 10)
)
ggplot(series, aes(time, value)) +
  geom_area(aes(fill = type))


# Stacking order ------------------------------------------------------------
# The stacking order is carefully designed so that the plot matches
# the legend.

# You control the stacking order by setting the levels of the underlying
# factor. See the forcats package for convenient helpers.
series$type2 <- factor(series$type, levels = c('c', 'b', 'd', 'a'))
ggplot(series, aes(time, value)) +
  geom_area(aes(fill = type2))


# You can change the order of the levels in the legend using the scale
ggplot(series, aes(time, value)) +
  geom_area(aes(fill = type)) +
  scale_fill_discrete(breaks = c('a', 'b', 'c', 'd'))


# If you've flipped the plot, use reverse = TRUE so the levels
# continue to match
ggplot(series, aes(time, value)) +
  geom_area(aes(fill = type2), position = position_stack(reverse = TRUE)) +
  coord_flip() +
  theme(legend.position = "top")


# Non-area plots ------------------------------------------------------------

# When stacking across multiple layers it's a good idea to always set
# the `group` aesthetic in the ggplot() call. This ensures that all layers
# are stacked in the same way.
ggplot(series, aes(time, value, group = type)) +
  geom_line(aes(colour = type), position = "stack") +
  geom_point(aes(colour = type), position = "stack")


ggplot(series, aes(time, value, group = type)) +
  geom_area(aes(fill = type)) +
  geom_line(aes(group = type), position = "stack")


# You can also stack labels, but the default position is suboptimal.
ggplot(series, aes(time, value, group = type)) +
  geom_area(aes(fill = type)) +
  geom_text(aes(label = type), position = "stack")


# You can override this with the vjust parameter. A vjust of 0.5
# will center the labels inside the corresponding area
ggplot(series, aes(time, value, group = type)) +
  geom_area(aes(fill = type)) +
  geom_text(aes(label = type), position = position_stack(vjust = 0.5))


# Negative values -----------------------------------------------------------

df <- tibble::tribble(
  ~x, ~y, ~grp,
  "a", 1,  "x",
  "a", 2,  "y",
  "b", 1,  "x",
  "b", 3,  "y",
  "b", -1, "y"
)
ggplot(data = df, aes(x, y, group = grp)) +
  geom_col(aes(fill = grp), position = position_stack(reverse = TRUE)) +
  geom_hline(yintercept = 0)


ggplot(data = df, aes(x, y, group = grp)) +
  geom_col(aes(fill = grp)) +
  geom_hline(yintercept = 0) +
  geom_text(aes(label = grp), position = position_stack(vjust = 0.5))