R function to plot win probabilities for a specific baseball game

graph.game.R

graph.game <- function(d, game.id){
  require(ggplot2)
  d1 <- subset(d, substr(HALF.INNING, 1, 12) == game.id)
  d1$Play <- 1:dim(d1)[1]
  yr <- substr(d1[1, "HALF.INNING"], 4, 7)
  mo <- substr(d1[1, "HALF.INNING"], 8, 9)
  day <- substr(d1[1, "HALF.INNING"], 10, 11)
  print(ggplot(d1, aes(Play, P.NEW)) + geom_line() + 
    ylim(0, 1) + geom_hline(yintercept=0.5, color="red") +
    ylab("Probability Home Team Wins") +
    labs(title = paste(d1[1, "AWAY_TEAM_ID"], "AT",
                     substr(d1[1, "HALF.INNING"], 1, 3),
                     "--", mo, "/", day, "/", yr )))
  d1
}