gganimate not showing all frames

Question

I'd like to make a simple gif with 138 states. I don't need any fancy transitions between each state, but I do need every state to appear in my gif. Currently, gganimate is cutting my gif short, not revealing the last ~30ish states.

Example

df <- lapply(1:138, function(t){
  data.frame(
    DT = as.POSIXct("2019-01-01 12:00:00", tz = "UTC") + t*24*60*60,
    x = seq(-3, 3, length.out = 100),
    y = t * seq(-3, 3, length.out = 100)
  )
})
df <- do.call(rbind, df)
range(df$DT)  # "2019-01-02 12:00:00 UTC" "2019-05-19 12:00:00 UTC"

p <- ggplot(data = df, mapping = aes(x = x, y = y)) + 
  geom_point()+ 
  transition_states(states = DT, transition_length = 0, state_length = 1)+
  labs(title = 'ScrapeDT: {previous_state}')
p

As you can see, the gif plays until about 2019-04-10, instead of 2019-05-19. I've also tried tinkering with animate() with no success. For example,

animate(
  plot = p, 
  nframes = length(unique(df$DT)), 
  fps = 8, 
  end_pause = 8
)

How can I make this work so that every desired state is shown for say, 0.25 seconds?

Answer 1

As stated in the docs, transition_manual() is exactly what you need:

This transition allows you to map a variable in your data to a specific frame in the animation. No tweening of data will be made and the number of frames in the animation will be decided by the number of levels in the frame variable.

Notice what I did below with transition_manual() and labs().

library(tidyverse)
library(gganimate)

df <- lapply(1:138, function(t){
  data.frame(
    DT = as.POSIXct("2019-01-01 12:00:00", tz = "UTC") + t * 24 * 60 * 60,
    x = seq(-3, 3, length.out = 100),
    y = t * seq(-3, 3, length.out = 100)
  )
})
df <- do.call(rbind, df)

p <- ggplot(data = df, mapping = aes(x = x, y = y)) + 
  geom_point()+ 
  transition_manual(frames = DT)+
  labs(title = 'ScrapeDT: {current_frame}')

animate(
  plot = p, 
  nframes = length(unique(df$DT)), 
  fps = 4, 
  end_pause = 8
)