# Josua Kugler, Christian Merten

library(tidyverse)

# a)
rate <- function(df, expr, name) {
    t <- summarize(df, total := sum({{expr}}))
    mutate(df, {{name}} := {{expr}} / t$total)
}

#b)
show_na <- function(df, expr) df %>% filter(is.na({{expr}}))

#c)
ggplot_line <- function(df, expr_x, expr_y)
    df %>% ggplot(aes(x = {{expr_x}}, y = {{expr_y}})) + geom_line()

#d)
athletes <- read_csv("athletes.csv")
medal_color <- c(Bronze = "#6A3805", Silver = "#B4B4B4", Gold = "#AF9500")

plot_olympia <- function(event, sex, metric) {
    athletes %>% filter(Event == event , Sex == sex) %>%
        mutate (Year = as.factor(Year)) ->
        d

    ggplot(d, aes(x = Year, y = {{metric}})) +
        geom_boxplot (na.rm = TRUE) +
        geom_point (data = drop_na (d), aes(color = Medal)) +
        scale_color_manual (values = medal_color) +
        ggtitle(str_c(event, sex, sep = ", "))
}