Here comes my solutions.


x <- c(33.75, 33.05, 34, 33.81, 33.46, 34.02, 33.68, 33.27, 33.49, 33.20, 33.62, 33.00, 33.54, 33.12, 33.84)


# clear space to start painting
dev.off()

# 1. solve the background color
qcc.options(bg.margin="white")

# 2. make plot with blank axis and set tick labels afterwards

par(xaxt="n")  #force plot to hide x-axis tick
q <-ewma(x, lambda=0.2, nsigmas=2.7,  add.stats=F)

par(xaxt="s")  # allow to have new x-axis tick
axis(1, at=c(1,5,15),label=c(1,5,15))  # create your own ticks

# 3. add legends anywhere you want, use expression() to type Greek letters
legend(10,33.8,expression("s = 5" ~lambda ~ " = 0.133" , "s = 6" ~lambda ~ " = 0.117" ),lty=1:2,col=1:2,lwd=1:2)

ewma是啥函数？

是qcc包中做质量控制的一个函数

看一下plot.qcc的代码

太感谢了，楼主真牛，向楼主学习