R/fish_fun.R

In Shuhanstack/mypack: Analyze fish, water, groundwate, and surveys

#' Analyze fish
#'
#' function returns the most common fish, the rarest fish, the total number of fish, and a histogram if asked
#' @param fish the vector of fish
#' @param plot whether to plot histogram or not; default is FALSE
#' @return a list containing the most common fish, the rarest fish, the total number of fish, and a histogram if asked
#' @examples fish_fun(fish = c("salmon", "salmon", "tuna", "tuna", "tuna", "cod"), plot=TRUE)
#' @author Shuhan Song and Annika Leiby

fish_fun = function(fish, plot=FALSE){
  # make sure fish is listed as factor in the vector
  fish_factor = as.factor(fish)

  # the most common fish
  most_common = names(which.max(summary(fish_factor)))

  # the rarest fish
  rarest = names(which.min(summary(fish_factor)))

  # total number of fish
  total_num = length(fish)

  # store the three items in a list
  fish_list = list("The most common fish" = most_common,
                   "The rarest fish" = rarest,
                   "Total number of fish" = total_num)

  # make a plot
  if(plot == TRUE){
    plottitle = sprintf("There is a total of %d fish.", total_num) # title name

    fish_plot = ggplot2::ggplot(data.frame(fish=fish),
                  ggplot2::aes(x = fish, fill = fish)) +
      ggplot2::geom_histogram(stat="count") +
      ggplot2::labs(title = plottitle) +
      ggplot2::theme_bw()

    # add histogram in the list
    fish_list$"Histogram" = fish_plot

  } else{
    fish_list$"Histogram" = NULL # make sure no histogram is returned in any other cases
  }

  return(fish_list)
}