ggplot2数据分析与图形艺术(学习笔记)

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https://github.com/hadley/ggplot2-book

Chapter 2

Chapter 2 ggplot2 入门

• ggplot2图像的三个基本构成
  1.数据
  2.图形属性映射，设定变量如何射映到图层的图形属性上
  3.几何对象，至少一层，用于指定绘图所用的几何对象

ggplot(mpg,aes(x = displ,y = hwy))+geom_point()

ggplot(economics,aes(date,unemploy))+geom_line()

ggplot(mpg,aes(cty))+geom_histogram()

ggplot(mpg,aes(displ,cty,colour=class))+
  geom_point()

ggplot(mpg,aes(displ,hwy)) + geom_point(aes(colour='blue'))

ggplot(mpg,aes(displ,hwy)) + geom_point(colour='blue')

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颜色和形状适合分类数据，大小适合连续数据

2.5 Facetting

ggplot(mpg,aes(displ,cyl))+ geom_point()+ facet_wrap(~class)

2.6 gemo( )

• 点图+平滑曲线

• method=“gam” 家在广义模型，用于大数据

ggplot(mpg,aes(displ,hwy))+
  geom_point()+
  geom_smooth()

geom_smooth()smooth程度可以调整

ggplot(mpg,aes(displ,hwy))+ geom_point()+ geom_smooth(span=0.2)

• 又或者把默认的lowess回归改成直线回归
  

  

2.6.2 Boxplots and jittered points

• 扰动点图geom_jitter()

• 箱线图geom_boxplot()

• 小提琴图geom_violin()
  可以更改colour和fill来调整轮廓和填充颜色

geom_point()	geom_jitter()	geom_boxploy()	geom_violin()

Histgrams and fréquencey polygons

ggplot(mpg,aes(hwy))+
  geom_histogram()

geom_histogram()	geom_freqpoly()

• geom_freqpoly()可以设置binwidth=

ggplot(mpg,aes(displ,colour=drv))+ geom_freqpoly(binwidth=0.5) ggplot(mpg,aes(displ,fill=drv))+ geom_histogram(binwidth=0.5)+ facet_wrap(~drv,ncol=1)

geom_freqpoly()	geom_histogram()

2.6.4 Bar Charts

ggplot(mpg, aes(manufacturer))+
  geom_bar()

2.6.5 Time series

year<-function(x)as.POSIXlt(x)$year+1900 ggplot(economics, aes(unemploy / pop, uempmed)) + geom_path(colour = 'grey50') + geom_point(aes(colour = year(date)))

2.7 修饰坐标轴

ggplot(mpg,aes(cty,hwy))+geom_point(alpha=1/3)

ggplot(mpg,aes(cty,hwy))+geom_point(alpha=1/3)+ xlab('city driving(mpg)')+ylab('highway driving(mpg)')

ggplot(mpg,aes(drv,hwy))+
  geom_jitter(width=0.25,na.rm=T)+
  xlim('f','r')+
  ylim(NA,30)

ggplot(mpg,aes(drv,hwy))+ geom_jitter(width=0.25,na.rm=T)+ ylim(NA,30)

2.8 输出

p<-ggplot(mpg,aes(displ,hwy,colour=factor(cyl)))+
  geom_point()
print(p)

• 保存

ggsave('plot.png',width=5,heigh=5)

2.9 快速绘图

qplot()

qplot(displ,hwy,data=mpg,colour='blue')

qplot(displ,hwy,data=mpg,colour=I('blue'))