Sample Mean Distribution -- Gamma

anim.R

library(tidyverse)
library(gganimate)

# Grid for plotting
x <- seq(0,10, length.out = 1e3)

# Sample Sizes
n <- 1:20

# Create the densities at each value of the grid
data <- map(n, ~tibble(x=x, y=dgamma(x, shape=3*.x, rate=1*.x)))

df <- 
  tibble(n, data) %>%
  unnest(data)

# Create animation
anim <- 
df %>%
  ggplot(aes(x=x, y=y)) +
  geom_line() +
  labs(subtitle = "Sample Size: {closest_state}",
       title = "Sampling distribution of the mean for i.i.d Gamma(3,1)",
       x= "x",
       y= "Probability Density",
       caption = "Sample Mean ~ Gamma(3n, n)") +
  cowplot::theme_cowplot(font_family = "Source Sans Pro",
                         font_size = 10) +
  theme(plot.title = element_text(size=10)) +
  theme(legend.position = "none")+
  transition_states(n, state_length = 1, transition_length = 2) +
  shadow_mark(alpha=0.3, color="gray") +
  ease_aes('quartic-in-out')

# Render animation
out <- animate(anim,
                 duration=10,
                 fps=60,
                 height = 3,
                 width = 4,
                 units = "in",
                 res = 300,
                 renderer = ffmpeg_renderer())

# Save to mp4
anim_save(animation = out, filename = "gamma_anim.mp4")