关于绘图区域

概念	英文	缩写函数	释义
主绘图	main plot area		类比画布，整块画布
绘图边距	margins	mar()	画布上想要画的地方的边距
外围边距	out margin area	oma()	画的图除了坐标轴外的画的东西

我们也可以用mai() and omi() 调整边缘，mai()与mar()的区别主要是单位的不同 ，oma与omi的区别主要也是是单位的不同
前者单位为文本行数，后者单位为英寸

一、上面那个图的代码，一行行运的话可以深刻体会画的是哪里

# Margins area 先把边缘确定
par(oma=c(3,3,3,3)) # all sides have 3 lines of space
par(mar=c(5,4,4,2) + 0.1)

# Plot 画图
plot(0:10, 0:10, type="n", xlab="X", ylab="Y") # type="n" hides the points

# Place text in the plot and color everything plot-related red
text(5,5, "Plot", col="red", cex=2)
box(col="red")

# Place text in the margins and label the margins, all in forestgreen  
mtext("Margins", side=3, line=2, cex=2, col="forestgreen")  
mtext("par(mar=c(b,l,t,r))", side=3, line=1, cex=1, col="forestgreen")  
mtext("Line 0", side=3, line=0, adj=1.0, cex=1, col="forestgreen")  
mtext("Line 1", side=3, line=1, adj=1.0, cex=1, col="forestgreen")  
mtext("Line 2", side=3, line=2, adj=1.0, cex=1, col="forestgreen")  
mtext("Line 3", side=3, line=3, adj=1.0, cex=1, col="forestgreen")  
box("figure", col="forestgreen")  

# Label the outer margin area and color it blue  
# Note the 'outer=TRUE' command moves us from the figure margins to the outer margins.  
mtext("Outer Margin Area", side=1, line=1, cex=2, col="blue", outer=TRUE)  
mtext("par(oma=c(bottom,left,to,right))", side=1, line=2, cex=1, col="blue", outer=TRUE)  
mtext("Line 0", side=1, line=0, adj=0.0, cex=1, col="blue", outer=TRUE)  
mtext("Line 1", side=1, line=1, adj=0.0, cex=1, col="blue", outer=TRUE)  
mtext("Line 2", side=1, line=2, adj=0.0, cex=1, col="blue", outer=TRUE)  
box("outer", col="blue")  

二、用其他图再次示例，先画一个散点图

plot(x=expdata[,1],y=expdata[,2], type="p", ann=T, axes=T,cex=0.2,
     main = "the compare of two sample's expression")`

box()函数可可视化plot绘图区域

# plot区域
box("plot", lty="dashed",col="red",lwd=3)

# figure区域
box("figure",col="blue",lwd=3)

# 绘图边距
box("outer", col="darkgreen",lwd=3)