Animated dot histogram, built observation by observation (using gganimate in R)

Question

I would like to sample points from a normal distribution, and then build up a dotplot one by one using the gganimate package until the final frame shows the full do

Answer 1

Try this. The basic idea is to the group the obs to frames, i.e. split by index and then accumulate the samples to frames, i.e. in frame 1 only the first obs is shown, in frame 2 obs 1 and 2, ..... Perhaps there is a more elegant way to achieve this, but it works:

library(ggplot2)
library(gganimate)
library(dplyr)
library(purrr)

set.seed(42)

# example data
samples <- rnorm(100)
index <- seq(1:length(samples))

# Put data into a data frame
df <- tibble(value=samples, index=index)

# inflated df. Group obs together into frames
df_ani <- df %>% 
  split(.$index) %>% 
  accumulate(~ bind_rows(.x, .y)) %>% 
  bind_rows(.id = "frame") %>% 
  mutate(frame = as.integer(frame))
head(df_ani)
#> # A tibble: 6 x 3
#>   frame  value index
#>      
#> 1     1  1.37      1
#> 2     2  1.37      1
#> 3     2 -0.565     2
#> 4     3  1.37      1
#> 5     3 -0.565     2
#> 6     3  0.363     3

p_gg <- ggplot(data=df, mapping=aes(x=value))+
  geom_dotplot()
p_gg
#> `stat_bindot()` using `bins = 30`. Pick better value with `binwidth`.

p_anim <- ggplot(data=df_ani, mapping=aes(x=value))+
  geom_dotplot()

anim <- p_anim + 
  transition_manual(frame) +
  ease_aes("linear") +
  enter_fade() +
  exit_fade()
anim
#> `stat_bindot()` using `bins = 30`. Pick better value with `binwidth`.

^{Created on 2020-04-27 by the reprex package (v0.3.0)}