Game simulation

# From @nnstats on Twitter
# Imagine a hockey game where we know that Team A scores exactly 1 goal for sure and Team B takes 20 shots, 
# each with a 5.5% chance of going in.
# Which team would you rather be?
# (nothing additional happens if you tie.)

library(tidyverse)
library(gganimate)

set.seed(1234)
team_b_goals <- NULL

for(i in 1:10000) {
  score <- sum(sample(c(1, 0), size = 20, replace = TRUE, prob = c(0.055, 1-.055)))
  team_b_goals <- c(team_b_goals, score)}

team_a_goals <- rep(1, 10000)
all_games <- as_tibble(cbind(team_a_goals, team_b_goals))

# Calculate cumulative sum of each Team's goals
all_games <- all_games %>% 
  mutate(team_a_wins = team_a_goals > team_b_goals,
         team_b_wins = team_b_goals > team_a_goals) 

all_games$game_number <- seq(1:10000)
all_games$team_a_wins <- cumsum(all_games$team_a_wins)
all_games$team_b_wins <- cumsum(all_games$team_b_wins)

small_data <- tibble(c(all_games$team_a_wins, all_games$team_b_wins), 
                    c(rep("Team_A", 10000), rep("Team_B", 10000)),
                    c(seq(1:10000), seq(1:10000)))

colnames(small_data) <- c("Points", "Team", "Game")

small_data %>% # add filter(Game < 1001) %>% to plot the first 1000 games only
  ggplot(aes(x = Points, y = Game, group = Team, colour = Team)) +
  geom_point() +
  geom_line(size = 2) + 
  coord_flip() +
  transition_reveal(Game) +
  shadow_mark(past = TRUE) +
  labs(title = "Wins of Team A vs. Team B", 
       x = "Running total of wins",
       y = "Game number") +
  theme(text = element_text(size = 15))