R：plot.ts（）的ylab中的希臘字母

Question

plot.ts()提供了一種方便的方法來可視化多元時間序列。 不幸的是，我不知道如何用希臘字母注釋（重復的）水平軸。 插入希臘字母的熟悉方法似乎行不通，我嘗試過的一些不太聰明的方法也行不通：

testdata = matrix(rnorm(300), ncol = 3)
# doesn't work
plot.ts(testdata, ylab = expression(paste(pi[0], " = 0")))
# doesn't work
plot.ts(testdata, ylab = c(expression(paste(pi[0], " = 0")),
                           expression(paste(pi[0], " = 1")),
                           expression(paste(pi[0], " = 2"))))
# doesn't work
colnames(testdata) = c(expression(paste(pi[0], " = 0")),
                       expression(paste(pi[0], " = 1")),
                       expression(paste(pi[0], " = 2")))
plot.ts(testdata)
# doesn't work
plot.ts(testdata, ylab = parse(text = y))

我的想法用光了...

Answer 1

有使用library(zoo)的解決方案library(zoo)

testdata = matrix(rnorm(300), ncol = 3)
plot(zoo::as.zoo(testdata),ylab=c(expression(mu),expression(sigma),expression(beta)),main="Win!")

改編自http://r.789695.n4.nabble.com/How-to-change-the-label-in-plot-ts-td796114.html