GGanimate: geom_text with numeric values animates at decimal numbers instead of integers

Question

Data <- data.frame(Time = c(1, 1, 1, 2, 2, 2, 3, 3, 3),
                   Group = c("A", "B", "C", "A", "B", "C", "A", "B", "C"),
                   Value = c(20, 10, 15, 20, 20, 20, 30, 25, 35))

I have three Groups with Values at three different points in Time.

library(ggplot2)
library(gganimate)

p <- ggplot(Data, aes(Group, Value)) +
     geom_col(position = "identity") +
  geom_text(aes(label = Value), vjust = -1) +
     coord_cartesian(ylim = c(0, 40)) +
     transition_time(Time)
p 

The above code produces the animation for the transformation of the bars quite well, but the change in the geom_text leaves much to be desired, as the geom_text tweens/transitions with >10 decimal places. Ideally I want the geom_text numeric values to remain as an integer whilst transitioning, or some way to control the degree of rounding.

Edit: Changing Value to an integer type doesn't help.

Answer 1

You can try to calculate the transitions by your own beforehand...

library(gganimate)
library(tidyverse)
Data2 <- Data %>% 
  group_by(Group) %>% 
    arrange(Group) %>% 
    mutate(diff = c((Value - lag(Value))[-1],0))

Seq <- seq(1,3,0.01)
library(gganimate)
tibble(Time_new=rep(Seq,3), Group = rep(LETTERS[1:3], each = length(Seq))) %>% 
  mutate(Time=as.numeric(str_sub(as.character(Time_new),1,1))) %>% 
  left_join(Data2)  %>%
  group_by(Group, Time) %>% 
  mutate(diff = cumsum(diff/n())) %>% 
  mutate(Value2 = Value + diff) %>%
  mutate(new_old = ifelse(Time == Time_new, 2, 1)) %>% 
  ggplot(aes(Group, Value2)) +
  geom_col(position = "identity") +
  geom_text(aes(label = sprintf("%1.2f",Value2)), vjust = -1) +
  coord_cartesian(ylim = c(0, 40)) +
  transition_manual(Time_new) 

or try geom_text(aes(label = round(Value2,2)), vjust = -1)