R语言gganimate包transition_reveal()未遵循x轴排序问题求助

核心问题原因 #

transition_reveal() 函数是按照传入参数的数值从小到大顺序逐步展示画面，你之前传入的是载客量stop_charge，这个值在有轨电车线路后半段会逐渐下降，导致动画不会按照站点顺序推进，反而会跳回前面的位置。

解决方法 #

仅需调整两处代码即可：

1. 保留数据中的站点顺序字段stop_order，该字段本身是单调递增的，完全匹配站点的运行顺序
2. 将transition_reveal()的参数替换为stop_order

修正后的完整代码如下：

library(tidyr)
library(dplyr)
library(ggplot2)
library(gganimate)

tramway_df <- data.frame(
  stop_order = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17),
  stop_id = c(9943, 5041, 5361, 2902, 2903, 5872, 5802, 5803, 5804, 5805, 
               5710, 5711, 5712, 1643, 5714, 521, 529),
  stop_name = c("DA VINCI", "DA VINCI", "BORDET STATION", "VAN CUTSEM", "FONSON", "PAIX", 
            "TILLEUL", "HELMET", "FOYER SCHAERBEEK.", "WAELHEM", "VERBOEKHOVEN", "PAVILLON",
            "RUBENS", "LIEDTS", "THOMAS", "GARE DU NORD", "ROGIER"),
  stop_in = c(27, 102, 153, 141, 190, 317, 379, 438, 328, 214, 278, 298, 154, 144, 162, 185, 0),
  stop_out = c(0, 7, 3, 10, 22, 37, 81, 122, 143, 168, 291, 230, 149, 301, 412, 707, 821),
  stop_charge = c(27, 121, 271, 402, 571, 851, 1149, 1465, 1650, 1696, 1682, 1745, 1750, 1592, 1342, 821, 0)
)

tramway_df %>% 
  gather(movement, value, stop_in:stop_out) %>% 
  # 用stop_order重排stop_id的因子顺序，避免原数据行序错乱导致x轴顺序错误
  mutate(stop_id = reorder(stop_id, stop_order)) %>% 
ggplot(aes(x=stop_id)) +
  geom_col(aes(y=value, fill = movement), position = "dodge", width = 1) +
  geom_line(aes(y=stop_charge, group=1)) + 
  scale_x_discrete(breaks = tramway_df$stop_id,
                   labels = tramway_df$stop_name) +
  # 替换为站点顺序字段，动画就会沿站点顺序推进
  transition_reveal(stop_order)

如果需要调整动画速度，可以在代码末尾加上animate(duration = 10, nframes = 100)，自行调整总时长和总帧数即可。

内容的提问来源于stack exchange，提问作者salwa