R/plot_logStrength.R

In LeoEgidi/footBayes: Fitting Bayesian and MLE Football Models

#' Plot Rankings for btdFoot Objects
#'
#' Visualizes team rankings based on whether the ranking is dynamic or static.
#'
#' \itemize{
#' \item Dynamic Ranking: Plots Rank Points over Periods for each team with lines and points.
#' \item Static Ranking: Plots Rank Points on the x-axis against Team Names on the y-axis with horizontal lines and points.
#' }
#'
#' @param x An object of class \code{btdFoot}.
#' @param teams An optional character vector specifying team names to include in the rankings plot. If \code{NULL}, all teams are included.
#'
#' @return A \code{ggplot} object:
#' \itemize{
#'   \item Dynamic BTD: A lineplot for the \code{log_strengths} over each period, colored by team.
#'   \item Static BTD: An horizontal barplot for each team.
#' }
#'
#' @author Roberto Macrì Demartino \email{roberto.macridemartino@deams.units.it}.
#'
#'
#' @examples
#' \dontrun{
#' if (instantiate::stan_cmdstan_exists()) {
#'   library(dplyr)
#'
#'   data("italy")
#'
#'   italy_2020_2021_rank <- italy %>%
#'     select(Season, home, visitor, hgoal, vgoal) %>%
#'     filter(Season == "2020" | Season == "2021") %>%
#'     mutate(match_outcome = case_when(
#'       hgoal > vgoal ~ 1, # Home team wins
#'       hgoal == vgoal ~ 2, # Draw
#'       hgoal < vgoal ~ 3 # Away team wins
#'     )) %>%
#'     mutate(periods = case_when(
#'       row_number() <= 190 ~ 1,
#'       row_number() <= 380 ~ 2,
#'       row_number() <= 570 ~ 3,
#'       TRUE ~ 4
#'     )) %>% # Assign periods based on match number
#'     select(periods,
#'       home_team = home,
#'       away_team = visitor, match_outcome
#'     )
#'
#'   fit_rank_dyn <- btd_foot(
#'     data = italy_2020_2021_rank,
#'     dynamic_rank = TRUE,
#'     rank_measure = "median",
#'     iter_sampling = 1000,
#'     parallel_chains = 2,
#'     chains = 2
#'   )
#'
#'   plot_logStrength(fit_rank_dyn)
#'
#'   plot_logStrength(fit_rank_dyn, teams = c("AC Milan", "AS Roma", "Juventus", "Inter"))
#' }
#' }
#'
#' @importFrom ggplot2 ggplot aes labs geom_line geom_point geom_segment theme_bw
#' theme element_text guides guide_legend
#' @importFrom rlang .data
#' @export

plot_logStrength <- function(x, teams = NULL) {
  # Check if the object is of class 'btdFoot'
  if (!inherits(x, "btdFoot")) {
    stop("Object must be of class 'btdFoot'.")
  }


  # Determine if the ranking is dynamic or static
  is_dynamic <- ifelse(length(unique(x$rank$periods, na.rm = TRUE)) > 1, TRUE, FALSE)

  # Handle teams
  if (!is.null(teams)) {
    # Check that specified teams exist
    available_teams <- unique(c(x$data$home_team, x$data$away_team))
    missing_teams <- setdiff(teams, available_teams)
    if (length(missing_teams) > 0) {
      stop(paste0("The following teams are not present in the data: ", paste(missing_teams, collapse = ", ")))
    }

    x$rank <- x$rank[x$rank$team %in% teams, ]
  }

  if (is_dynamic) {
    # Dynamic Ranking Plot
    p <- ggplot(x$rank, aes(x = .data$periods, y = .data$log_strengths, color = .data$team)) +
      geom_line() +
      geom_point() +
      labs(
        x = "Periods",
        y = "Log-Strength Values"
      ) +
      theme_bw() +
      theme(
        legend.position = "right",
        legend.title = element_text(size = 10),
        plot.title = element_text(hjust = 0.5)
      ) +
      scale_x_continuous(breaks = sort(unique(x$rank$periods))) +
      guides(
        color = guide_legend(title = "Team")
      )
  } else {
    # Static Ranking Plot
    p <- ggplot(x$rank, aes(y = stats::reorder(.data$team, .data$log_strengths), x = .data$log_strengths)) +
      geom_segment(
        aes(x = 0, xend = .data$log_strengths, yend = .data$team),
        color = "deepskyblue4",
        linewidth = 1
      ) +
      geom_point(
        color = "firebrick4",
        size = 3
      ) +
      labs(
        x = "Log-Strength Values",
        y = "Teams"
      ) +
      theme_bw() +
      theme(
        legend.position = "none",
        plot.title = element_text(hjust = 0.5)
      )
  }

  return(p)
}