gganimate：如何使堆积条形图从 x 轴向上平滑增长

Question

我在为堆叠的 static plot 设置动画时遇到问题。 （见下文 animation）

animation 从左到右以不稳定的方式移动，而不是每个条从 x 轴向上增长。 堆叠的部分也不会很顺利地一起生长，我似乎无法解决。

我需要在我的代码中进行哪些更改，以便随着动画 plot 沿 x 轴过渡，各个条形向上增长？ 我还想让堆叠的条更平滑地增长，所以堆叠的条部分不会“扔”在彼此的顶部。

这怎么可能？

本文顶部的 gif 是我正在寻找的，但我不明白他的代码与我的代码有何不同以及在哪里：理想 animation

这是我的代表：

#Static df
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
year <- as.numeric(c(1996:2015,
                       1996:2015,
                       1996:2015))
c <- c(39, 40, 67, 80, 30, 140, 90, 23, 100, 123,
       140, 160, 100, 89, 173, 200, 32, 90, 100, 211,
       1, 2, 1, 13, 3, 3, 30, 1, 3, 3,
       1, 1, 20, 2, 1, 10, 1, 2, 1, 1,
       1, 3, 1, 2, 1, 3, 1, 3, 6, 1,
       1, 30, 1, 1, 8, 9, 1, 32, 1, 1)
cat <- as.character(c("out", "out", "out", "out", "out", "out", "out", "out", "out", "out",
                   "out", "out", "out", "out", "out", "out", "out", "out", "out", "out",
                   "in", "in", "in", "in", "in", "out", "in", "in", "in", "in",
                   "in", "in", "in", "in", "in", "in", "in", "in", "in", "in",
                   "other", "other", "other", "other", "other", "other", "other", "other", "other", "other",
                   "other", "other", "other", "other", "other", "other", "other", "other", "other", "other"))
cat <- as.factor(cat)
static_df_test <- data.frame(year, c, cat) %>%
  select(year, cat, c) %>%
  arrange(year, cat)


#Static plot
library(ggplot2)
(static_plot <- ggplot(static_df_test) +
    geom_bar(data = static_df_test, stat="identity", position ="stack",
             aes(x = year, y = c, fill = cat)) +
    scale_x_continuous(breaks = seq(1996, 2015, 1),
                       expand = c(0.003, 0.003),
                       labels = c(1996, 97, 98, 99, 2000,
                                  "01", "02", "03", "04", "05", "06",
                                  "07", "08", "09", 10, 11, 12, 13, 14, 15)) +
    scale_y_continuous(breaks = seq(0, 250, 25),
                       expand = c(0,0),
                       limits = c(0,250)) +
    labs(x = "year", y = "c")
)

#Animated plot
library(gganimate)
library(ggplot2)
ani <- (static_plot) +
  transition_time(as.integer(year)) +
  enter_grow() + shadow_mark(past = TRUE)

animate(ani, fps = 8, 50, duration = 15,
        width = 1500, height = 750, renderer = gifski_renderer())

现在，条形图通过从上一个条形向右移动来过渡。 在此处查看当前的 animation：

预先感谢您的任何帮助！

Answer 1

可能有更正确的方法可以做到这一点，但可以通过更改构建初始 static plot 的方式并使用transition_layers()和enter_drift()来完成。

请注意，为了简化我的示例，我只包括 1996-2000 年。 要为所有年份设置动画，只需复制并粘贴geom_bar()部分并更改被过滤的年份。

#Static plot
library(ggplot2)
(static_plot <- ggplot(static_df_test) +
    geom_bar(data = static_df_test %>% filter(year == 1996), stat="identity", position ="stack",
             aes(x = year, y = c, fill = cat)) +
    geom_bar(data = static_df_test %>% filter(year == 1997), stat="identity", position ="stack",
             aes(x = year, y = c, fill = cat)) +
    geom_bar(data = static_df_test %>% filter(year == 1998), stat="identity", position ="stack",
             aes(x = year, y = c, fill = cat)) +
    geom_bar(data = static_df_test %>% filter(year == 1999), stat="identity", position ="stack",
             aes(x = year, y = c, fill = cat)) +
    geom_bar(data = static_df_test %>% filter(year == 2000), stat="identity", position ="stack",
             aes(x = year, y = c, fill = cat)) +
    scale_x_continuous(breaks = seq(1996, 2015, 1),
                       expand = c(0.003, 0.003),
                       labels = c(1996, 97, 98, 99, 2000,
                                  "01", "02", "03", "04", "05", "06",
                                  "07", "08", "09", 10, 11, 12, 13, 14, 15)) +
    scale_y_continuous(breaks = seq(0, 250, 25),
                       expand = c(0,0),
                       limits = c(0,250)) +
    labs(x = "year", y = "c")
)

#Animated plot
library(gganimate)
library(ggplot2)

ani <- (static_plot) +
  transition_layers(layer_length = 1, transition_length = 2) +
  enter_drift(x_mod = 0, y_mod = -max(static_df_test$c))

animate(ani, fps = 10, duration = 10,
        width = 600, height = 500, renderer = gifski_renderer())

通过将每个基于年份的条形图放置在其自己的图层上，我们可以使用transition_layers()使它们一一出现，同时保留所有旧图层。 我们使用enter_drift()为每个条设置动画，就好像它从图表下方向上漂移一样。

动画 output 在这里：链接

Answer 2

有一个更简单的解决方案。 将您的“年份”变量视为一个因素而不是数字。 这将使酒吧像你想要的那样平稳地向上增长。

基本上为您的 static plot 代码使用以下块，它将起作用：

static_plot <- ggplot(static_df_test) +
    geom_bar(data = static_df_test, stat="identity", position ="stack",
             aes(x = as.factor(year), y = c, fill = cat)) +
    scale_y_continuous(breaks = seq(0, 250, 25),
                       expand = c(0,0),
                       limits = c(0,250)) +
    labs(x = "year", y = "c")

我知道我有点晚了，但我希望它有所帮助。