R4DS-学习记录-ggplot2_2-CG

练习思路和数据完全来自于R4DS(R for data science)教材

加载R包

library(tidyverse)
library(palmerpenguins)
library(ggthemes)

1. categorical variable

变量（variable）的值（value）较少时。明确的结果。

ggplot(penguins, aes(x = species)) +
  geom_bar()#non-ordered levels

• Doing so requires transforming the variable to a factor (how R handles categorical data) and then reordering the levels of that factor.

ggplot(penguins, aes(x = fct_infreq(species))) +
  geom_bar()#转换因子

2. A numerical variable

A variable is numerical (or quantitative) if it can take on a wide range of numerical values，visualization for distributions of continuous variables is a histogram.

> ggplot(penguins,aes(x=body_mass_g))+
+   geom_histogram()
#`stat_bin()` using `bins = 30`. Pick better value with `binwidth`.
#Warning message:
#Removed 2 rows containing non-finite outside the scale range (`stat_bin()`). 
> ggplot(penguins,aes(x=body_mass_g))+
+   geom_histogram(binwidth = 200)

binwidth = 200

binwidth = 30

• shows fewer details than a histogram but can make it easier to quickly glean the shape of the distribution, particularly with respect to modes and skewness.

ggplot(penguins,aes(x = body_mass_g))+
  geom_density()

density!更重趋势，少细节

练习

1.

ggplot(penguins,aes(y = species))+
  geom_bar()

2.

分析那种加颜色的方式比较有用

ggplot(penguins, aes(x = species)) +
  geom_bar(color = "red")#红色描边

ggplot(penguins, aes(x = species)) +
  geom_bar(fill = "red")#红色填充

3.

What does the bins argument in geom_histogram() do?

It determines the number of bins (bars) in a histogram.

4. Make a histogram of the carat variable in the diamonds dataset that is available when you load the tidyverse package. Experiment with different binwidths. What binwidth reveals the most interesting patterns?