R语言与医学统计图形-【19】ggplot2坐标轴调节 R语言与医学统计图形-【19】

ggplot2绘图系统——坐标轴调节 scale函数：图形遥控器。坐标轴标度函数：
scale_x_continous
scale_y_continous
scale_x_discrete
scale_y_discrete
1. 连续型变量坐标轴
函数及其参数：

scale_x_continuous(name = , #坐标轴标签 breaks = , #定义刻度 minor_breaks = , labels = , #刻度标签 limits = , expand = c(0.05,0), #坐标轴延伸，确保图形元素不覆盖坐标 oob = censor,#识别越过边界的点 na.value = https://www.it610.com/article/NA_real_, trans ='identity', #统计变换 position = 'bottom', #left/right/top sec.axis = #定义第二坐标轴 )

统计变换参数备选：asn/atanh/boxcox/exp/identity/log/log10/log1p/log2/logit/probability/probit/reciprocal/reverse/sqrt

p1 <- ggplot(mpg,aes(displ,hwy))+geom_point() a=p1+scale_x_continuous('L')+ #同xlab scale_y_continuous("H")b=p1+scale_x_continuous(limits = c(0,10)) #同xlim c=p1+scale_x_continuous(breaks = c(2,4,6), labels = c('two','four','six')) gridExtra::grid.arrange(a,b,c,ncol=3)

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image.png 刻度标签转化为百分比
调用scales包中的percent函数。

prop <- data.frame(sex=rep(c('Male','Female'),each=5), age=rep(c('0-14','15-34','35-49','50-64','65+'),2), prop=c(0.12,0.37,0.23,0.17,0.11,0.09,0.33,0.28,0.21,0.09)) ggplot(prop,aes(x=age,weight=prop,fill=sex))+ geom_bar(position = 'dodge')+ scale_y_continuous(labels = scales::percent)+ ylab('Proportion')

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image.png 2. 离散型坐标轴
针对离散型变量，在条形图、盒形图中使用较多。

d <- ggplot(subset(diamonds,carat>1),aes(cut,clarity))+ geom_jitter()#重定义坐标轴标签 a=d+scale_x_discrete('Cut',labels=c('Fair'='F','Good'='G','Very Good'='VG', 'Premium'='P','Ideal'="I")) #取值范围，这里相当于取子集 b=d+scale_x_discrete(limits=c('Fair','Ideal'))grid.arrange(a,b,nrow=1)

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ggplot(mpg,aes(reorder(manufacturer,displ),cty))+ geom_point()+ scale_x_discrete(labels=abbreviate) #abbreviate函数缩写x轴标签

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image.png 3. theme函数调节坐标轴
标度函数和theme调节坐标轴分工稍有不同，前者用于框架搭建，后者用于细节修饰。
theme修饰坐标轴常用参数：

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应用示例。

p <- ggplot(mtcars,aes(mpg,wt))+geom_point() p+theme(axis.title = element_text(color = 'red',size=18), axis.line = element_line(color='blue'), axis.text = element_text(color = 'orange',size = 12), axis.ticks = element_line(color = 'light skyblue',size=3))