R语言-直方图

1.直方图

直方图和柱形图的区别：直方图表示频数，柱形图表示数量。

一般直方图的X轴表示取值范围，Y轴表示频数

hist() 函数

> hist(rnorm(1000))     #1000个正态随机数的直方图
> hist(islands)         #岛屿数据集直方图

                                    

2.概率密度直方图

> air<-read.csv("airpollution.csv")
> hist(air$Nitrogen.Oxides,
+ freq=FALSE,                          #不显示频数，显示概率
+ xlab="Nitrogen Oxide Concentrations",
+ main="Distribution of Nitrogen Oxide Concentrations")

3.调整直方图范围密度

> hist(air$Nitrogen.Oxides,
+ breaks=20,                            #设置范围数
+ xlab="Nitrogen Oxide Concentrations",
+ main="Distribution of Nitrogen Oxide Concentrations")

> hist(air$Nitrogen.Oxides,
+ breaks=c(0,100,200,300,400,500,600),   #指定范围
+ xlab="Nitrogen Oxide Concentrations",
+ main="Distribution of Nitrogen Oxide Concentrations")

4.直方图美化

①颜色美化

> hist(air$Respirable.Particles,
+ prob=TRUE,                            #纵坐标轴显示概率而不是频数
+ col="black",
+ border="white", xlab="Respirable Particle Concentrations",
+ main="Distribution of Respirable Particle Concentrations")

②线条美化

> par(yaxs="i",las=1)
> hist(air$Respirable.Particles, prob=TRUE,
+ col="black",border="white",
+ xlab="Respirable Particle Concentrations",
+ main="Distribution of Respirable Particle Concentrations")
> box(bty="l")             #设置坐标轴样式
> grid(nx=NA,ny=NULL,      #X轴没有线条，Y轴自动计算线条位置
+ lty=1,lwd=1,col="gray")  #设置线条的样式、宽度和颜色

5.标识密度函数Density()函数 

> par(yaxs="i",las=1)
> hist(air$Respirable.Particles,
+ prob=TRUE,col="black",border="white",
+ xlab="Respirable Particle Concentrations",
+ main="Distribution of Respirable Particle Concentrations")
+ box(bty="l")
> lines(density(air$Respirable.Particles,na.rm=T),  #density()作密度函数
+ col="red",lwd=4)
> grid(nx=NA,ny=NULL,lty=1,lwd=1,col=" gray")

6.散点图+直方图

> panel.hist <- function(x, ...)
+ {
+ par(usr = c(par("usr")[1:2], 0, 1.5) )
+ hist(x,
+ prob=TRUE,
+ add=TRUE,col="bla ck",border="white")
+ }
> plot(iris[,1:4],
+ main="Relationships between characteristics of iris flowers",
+ pch=19,col="blue",cex=0.9,
+ diag.panel=panel.hist)              #对角线画直方图

> layout(matrix(c(2,0,1,3),2,2,byrow=TRUE),
+ widths=c(3,1), heights=c(1,3), TRUE)
> par(mar=c(5.1,4.1,0.1,0))                     #画散点图
> plot(air$Respirable.Particles~air$Nitrogen.Oxides, pch=19,col="black", xlim=c(0,600),ylim=c(0,80),
+ xlab="Nitrogen Oxides Concentrations",
+ ylab="Respirable Particle Concentrations")
> par(mar=c(0,4.1,3,0))                         #画上方的直方图
> hist(air$Nitrogen.Oxides, breaks=seq(0,600,100),
+ ann=FALSE,axes=FALSE,                         #无注释，无坐标轴
+ col="black",border="white")
> yhist <- hist(air$Respirable.Particles,
+ breaks=seq(0,80,10),plot=FALSE)
> par(mar=c(5.1,0,0.1,1))                       #画右边的直方图
> barplot(yhist$density, horiz=TRUE,
+ space=0,axes=FALSE,
+ col="black",border="white")