第二个

png("2.png")
x1 <- 0.5
y1 <- 0.5
x2 <- 1
y2 <- 0.5
r1 <- 0.4
r2 <- 0.4
theta <- seq(0, 2*pi, length = 500)
x <- r1*cos(theta)+x1
y <- r1*sin(theta)+y1
xx <- r2*cos(theta)+x2
yy <- r2*sin(theta)+y2
plot(1, xlim = c(0, 1.5), ylim = c(0, 1.5), type = "n", asp = 1, axes = NA, )
rect(0, 0, 1.5, 1.5, col = "green")
polygon(x, y, col = "red")
polygon(xx, yy, col = "blue")
lab2 <- (xx-x1)^2+(yy-y1)^2 <= r1^2
lab1 <- (x-x2)^2+(y-y2)^2 <= r2^2
polygon(c(x[lab1][rank(y[lab1])], xx[lab2]), c(sort(y[lab1]), yy[lab2]), col = "yellow")
arrows(x1, y1, x1, y1+0.8, col = "red", lwd = 2)
arrows(x2, y2, x2, y2+0.8, col = "blue", lwd = 2)
arrows((x1+x2)/2, y1, (x1+x2)/2, y1+0.8, col = "yellow", lwd = 2)
text(c(x1, (x1+x2)/2, x2), c(y1+0.9, y1+0.9, y2+0.9), labels = c("A", "AB", "B"), col = c("red", "yellow", "blue"))
dev.off()

感谢版主，我和你写的程序类似，我觉得这样比较复杂，所以我才发帖提问。
不知道版主能不能用library(plotrix)下面的draw.circle()命令实现。
我也附上我自己写的比较复杂的程序，以供大家交流学习。
#图1：code

windows(height=4,width=4,points=9)
plot(c(-0.2,1.5),c(-0.2,1.5),type="n",axes=FALSE,xlab="",ylab="")
labels=c("t","T"); at=c(0.6,1); yat=c(0,0)-0.1
arrows(x0=0,y0=0, x1=1.4, y1=0,length=0.08, lwd=2)
text(at,yat,labels)
arrows(x0=0,y0=0, x1=0, y1=1.4,length=0.08, lwd=2)
text(yat,at,labels)
polygon(c(0,1,1,0), c(0,0,1,1))
text(-0.1,-0.1,expression(0))
abline(a=-0.6,b=1, lty=2)      # or segments()
text(1.2,0.3,expression(y==x-t),cex=1.2)
abline(a=0.6, b=1, lty=2)
text(0.5,1.4,expression(y==x+t),cex=1.2)
xnew=c(0, 0.6, 1, 1, 0.4, 0, 0)
ynew=c(0, 0, 0.4, 1, 1, 0.6, 0)
polygon(xnew,ynew, col="gray")
text(c(1.4,-0.1),c(-0.1, 1.4), c("x","y"),cex=1.2, font=4)

# 图2：code
x=seq(0,2,length=100)
y1=1+sqrt(1-(x-1)^2)
y2=1-sqrt(1-(x-1)^2)
t=1+seq(0,2,length=100)
s1=1+sqrt(1-(t-2)^2)
s2=1-sqrt(1-(t-2)^2)

x1=x[which(x>=1)]
t1=t[which(t<=2)]
a1=y2[which(x>=1)]
a2=s2[which(t<=2)]
j=which.min(abs(a1-a2))
xnew=c(x1[1:j],t1[(j+1):length(t1)])
ynew1=c(s2[1:j],y2[(100-j+1):100])
ynew2=c(s1[1:j],y1[(100-j+1):100])
windows(height=4,width=4,points=9)
plot(c(-0.3,3.7),c(-0.3,3.7),type="n",axes=FALSE,xlab="",ylab="")
polygon(c(-0.2,3.5,rev(c(-0.2,3.5))), c(-0.2,-0.2,rev(c(3,3))), col=3, border = 3)
text(3.1,2.8,expression(Omega),col=1)
polygon(c(x,rev(x)), c(y1,rev(y2)), col=2, border = 2)
polygon(c(t,rev(t)), c(s1,rev(s2)), col=4, border = 4)
polygon(c(xnew, rev(xnew)), c(ynew1,rev(ynew2)),col=7, border=7)
arrows(x0=0.6,y0=1.2,x1=0.95,y1=2.5,col=2,length=0.08)
text(1,2.7,expression(A),col=2)
arrows(x0=2.5,y0=1.1,x1=2.5,y1=2.5,col=4,length=0.08)
text(2.5,2.7,expression(B),col=4)
arrows(xnew[j],ynew2[j],xnew[j]+0.1,2.5,col=7, length=0.08)
text(xnew[j]+0.1,2.7, expression(AB),col=7)

draw.circle()可以画出两个圆形，但是中间的重叠部分没办法搞定。

我也正是想怎么解决公共部分的问题

你可以把你的程序写成一个函数就方便以后使用了。

第二个图可以看看vennDiagram这个包

受大家启发，要不把颜色拿掉怎么样？


require(plotrix)
plot(1, xlim = c(0, 5), ylim = c(0, 5), type = "n", asp = 1, axes=NA,)
draw.circle(1,2,1.5,nv=100,border='black',col=NA,lty=1,lwd=1)
draw.circle(3,2,1.5,nv=100,border='black',col=NA,lty=1,lwd=1)
arrows(1,3,.8,4)
arrows(2,3,2,4)
arrows(3,3,3.2,4)
text(c(.8,2,3.2),c(4.2,4.2,4.2),labels=c('A','AB','B'))

好像也没有方便的哟，这个命令也很复杂

没注意楼上这位的意见，确实一条命令就搞定了，真是high-resolution

require(VennDiagram)
venn.plot=draw.pairwise.venn(
        area1 = 100,
        area2 = 100,
        cross.area = 30,
        fill = c("blue", "red"),
      lty='blank',
        category=c('A','B'),
        cat.cex = 2,
        cat.pos = c(340, 14),
        cat.dist = 0.09,
        )

而且比较好看

呵呵，不错，我刚开始也尝试只用两个area1和area2，但是不知道加cross.area = 30，cat.cex = 2,，就没整出来，以后还得多多学习请教啊