如何在熱圖上顯示特殊字符

Question

我有一個如下所示的數據框：

                        V2   V3 V4   V5   V6    V7
PPAR Signaling        1.32 1.41  0 1.61 1.36 1.210
PPARα/RXRα Activation 0.00 0.00  0 1.34 1.10 0.944

使用此代碼：

    dat <- structure(list(V2 = c(1.32, 0), V3 = c(1.41, 0), V4 = c(0L, 0L
    ), V5 = c(1.61, 1.34), V6 = c(1.36, 1.1), V7 = c(1.21, 0.944)), .Names = c("V2", 
    "V3", "V4", "V5", "V6", "V7"), row.names = c("PPAR Signaling", 
    "PPARα/RXRα Activation"), class = "data.frame")


   ## Actual data can be found here http://dpaste.com/2AYAPSX/

   ## In reality the data is read using 
   # dat <- read.table("http://dpaste.com/2AYAPSX/",sep="\t")
   # dat(rownames) <- dat$V1
   # dat$V1 <- NULL

    heatmap(as.matrix(dat))

它產生這樣的熱圖：

請注意，希臘字母已更改為.. 。 如何正確顯示希臘字母？

更新：會話信息

> sessionInfo()
R version 3.0.2 (2013-09-25)
Platform: x86_64-apple-darwin10.8.0 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

Answer 1

嘗試

heatmap(as.matrix(dat), labRow =c("PPAR Signaling",
                                   expression(paste("PPAR",alpha,"/RXR", alpha, " Activation"))))