Part 1 Exercise 3: Playing with scales and color

Exercise 3.1

ggplot(nass.cotton, aes(year, yield)) + 
  geom_point(aes(color = acres)) + 
  facet_wrap(~state) + 
  scale_y_log10(name = "Yield") + 
  scale_color_continuous_sequential(palette = "ag_GrnYl",
                                    trans = "log10",
                                    breaks = trans_breaks("log10", function(x) 10^x),
                                    labels = trans_format("log10", math_format(10.^.x))) +
  labs(x = "Year", title = "US Cotton Yields", subtitle = "1900 to 2011") 

Exercise 3.2

# drop the state so it doesn't get facet wrapped
shadow_dat <- nass.cotton %>% mutate(state = NULL) 
ggplot(nass.cotton, aes(year, acres)) +
  geom_point(data = shadow_dat, color = "gray") +
  geom_point() +
  facet_wrap(~state) + 
  scale_y_log10() + 
  labs(y = "Acres", x = "Year",
       title = "US Land for Cotton Farm", subtitle = "1900 to 2011")

Exercise 3.3

ggplot(hazell.vegetables, aes(year, celery, fill = celery > 0)) + 
  geom_col() + 
  geom_hline(yintercept = 0) + 
  scale_y_continuous(labels = dollar) + 
  labs(y = "Gross profit", x = "Year",
       title = "Celery", fill = "Profit") +
  scale_fill_manual(labels = c("No", "Yes"),
                    values = c("#ff1a1a", "#008000")) +
  scale_x_discrete(labels = 1:6)

Exercise 3.4

ggplot(hanks.sprinkler, aes(factor(row), factor(subplot))) +
  geom_tile(aes(fill = dir)) +
  geom_point(aes(color = factor(irr)), size = 9) +
  geom_text(aes(label = block)) +
  scale_fill_manual(values = c("black", "gray"), 
                    name = "Direction of\n sprinkler") + 
  scale_color_discrete_qualitative(palette = "Set 3") +
  labs(x = "Row", y = "Subplot", color = "Irrigation") + 
  # so that color legend appears before the fill legend
  guides(fill = guide_legend(order = 2),
         color = guide_legend(order = 1))

Exercise 3.5

df <- minnesota.barley.weather %>% 
  mutate(date = as.Date(paste(year, mo, "01", sep = "-")))
  
farenheight_to_celsius <- function(x) return((x - 32) * 5/9) 

ggplot(df, aes(x = date)) + 
  geom_line(aes(y = farenheight_to_celsius(min)), color = "#166ee0") + 
  geom_line(aes(y = farenheight_to_celsius(max)), color = "#e0161d")  + 
  facet_wrap(~site) + 
  scale_y_continuous(name = "Temperature",
                     label = function(x) paste0(x, "°C")) +
  scale_x_date(breaks = scales::date_breaks(width = "3 year"),
               date_labels = "%Y",
               name = "Time")  +
  ggtitle("Minnesota Monthly Temperature 1927-1936")