Reordering bars in GGanimate visualization

Last week several gganimate visualizations came to my feed. Some R users were wondering about reordering gganimate and ggplot2 bars as long as them are evolving (over animation time).

Then, we came up with this R viz where several bars are not only evolving and reordering over time but leaving and joining the chart. We want the top 4 countries over time, then the remaining countries in each timestamp should leave.

You can achieve this effect and this kind of gganimate visualization following this commented code:

library(ggplot2)
library(gganimate)
library(tidyverse)
df_evolution_data <- data.frame(Name=rep(c("Madrid","Barcelona",
                              "Valencia","Alicante",
                              "Sevilla"),5),
                   Year = factor(sort(rep(2001:2005, 5))),
                   Value = runif(25,100,1000))

df_evolution_data_filtered <- df_evolution_data %>%
  group_by(Year) %>%
  mutate(Rank = rank(Value)) %>% # Rank 1 the lowest 5 the higest
  filter(Rank >= 2)              # Top 4 countries

ggplot(df_evolution_data_filtered) +
  geom_col(aes(x=Rank, y=Value,
               group=Name, fill=Name),
           width=0.4) +
  geom_text(aes(x=Rank, y=0,
                label=Name, group=Name),
            hjust=1.25) +
  theme_minimal() + ylab('Value') +
  theme(axis.title.y = element_blank(),
        axis.text.y = element_blank(),
        axis.ticks.y = element_blank(),
        plot.margin = unit(c(5,5,5,5),
                           'lines')) +
  scale_fill_brewer(palette="Dark2") +
  coord_flip(clip='off') + 
  ggtitle('{closest_state}') +             # title with the timestamp period
  transition_states(Year,
                    transition_length = 1,
                    state_length = 1) +
  exit_fly(x_loc = 0, y_loc = 0) +         # chart exit animation params
  enter_fly(x_loc = 0, y_loc = 0)          # chart enter animation params

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