修复动画ggplot中的突然变化/过渡

Question

我想为一年中的国家/地区制作每日价值的动画 ggplot。多亏了一些有用的问题/答案here，我才能做到这一点。

虽然下面的代码成功制作了 gif，但当国家/地区上下移动/超越彼此时的变化/过渡非常突然（即瞬时）。它不像链接帖子中的示例那样流畅。

我不完全确定为什么会发生这种情况，非常感谢一些帮助。提前感谢任何能够提供一些见解的人。代码如下。

library(tidyverse)
library(ggplot2)
library(gganimate)
library(gifski)
library(png)

# Generate some fake data 
n=365  
df <- data.frame(country_name = rep(c("Country_1","Country_2","Country_3","Country_4","Country_5"), n, replace=FALSE),
                 date = rep(seq.Date(as.Date("2021-01-01"), as.Date("2021-12-31"), "day"),each=5), # each is number of countries 
                 incidents=sample(1:100, size = 25, replace=TRUE
                 ))

# Make cumulative number of events
df = df %>% 
  group_by(country_name) %>%
  arrange(date) %>%
  mutate(cumulative_incidents = cumsum(incidents)) %>%
  ungroup()

# create integer rankings (I thought the *1 would make things smoother)
df = df %>% 
  group_by(date) %>%
  mutate(rank = min_rank(-cumulative_incidents *1), 
         Value_rel = cumulative_incidents/cumulative_incidents[rank==1],
         Value_lbl = paste0(" ",round(cumulative_incidents/1e9))) %>%
  ungroup()
 
# make the static plot
my_plot = ggplot(df, aes(-rank,Value_rel, fill = country_name)) +
  geom_col(width = 0.8, position="identity") +
  coord_flip() + 
  geom_text(aes(-rank,y=0,label = country_name,hjust=0)) +       
  geom_text(aes(-rank,y=Value_rel,label = cumulative_incidents, hjust=0)) + 
  theme_minimal() +
  theme(legend.position = "none",axis.title = element_blank()) +
  # animate along Year
  transition_states(date,4,1)

# animate the plot
animate(my_plot, 100, fps = 25, duration = 20, width = 800, height = 600)

Answer 1

您的数据的时间分辨率非常高，您有 365 个时间点，但动画中只有 500 帧。因此，这些平滑切换发生在 500 / 365 = ~1.4 帧内并且不可见。

要么使您的动画更长，降低数据的时间分辨率，要么在过渡中手动编码。例如，如果我们每月只提供一次数据，会发生以下情况：

df2 <- filter(df, date %in% seq(min(date), max(date), 'week'))
my_plot <- ggplot(df2, aes(-rank,Value_rel, fill = country_name)) +
  geom_col(width = 0.8, position="identity") +
  coord_flip() + 
  geom_text(aes(-rank,y=0,label = country_name,hjust=0)) +       
  geom_text(aes(-rank,y=Value_rel,label = cumulative_incidents, hjust=0)) + 
  theme_minimal() +
  theme(legend.position = "none",axis.title = element_blank()) +
  # animate along Year
  transition_states(date, transition_length = 10, state_length = 1)
animate(my_plot, fps = 25, duration = 20, width = 800, height = 600)