ggplot2介绍入门

1. Histogram

A simple histogram is like this:

# load the dataset
data(midwest)
hist(midwest$percbelowpoverty, main = "A simple histogram",xlab = "Percentage below poverty" )

ggplot(data = midwest, 
       mapping = aes(x = percbelowpoverty)) + 
  theme_bw() +
  geom_histogram(aes(y = ..density.., fill = percbelowpoverty)) +
  labs(x = "Poverty Percentage", y = "Counts", title = "this plot") +
  geom_density(aes(y = ..density..),col = "red", fill = "red", alpha = 0.5)

midwest2 <- midwest %>% 
  mutate(bluepoint = ifelse(perchsd > 70 & percbelowpoverty < 20, 1, 0))
ggplot(midwest2,
       aes(x = percbelowpoverty,
           y = perchsd)) + 
  geom_point(aes(col = as.factor(state)), size = 2) +
  geom_smooth(col = "red", se = FALSE)

class_agg <- data.frame(table(mpg$class))
colnames(class_agg) <- c("a", "b")
ggplot(class_agg, aes(x = a, y = b)) + geom_bar(stat = "identity", aes(fill = a )) +
  scale_fill_brewer(type = "qual", palette = 4, direction = -1)