> x.Date <- as.Date(paste(2003, 02, c(1, 3, 7, 9, 14), sep = "-"))

> x <- zoo(rnorm(5), x.Date)

> x

2003-02-01  2003-02-03  2003-02-07  2003-02-09  2003-02-14

-0.75942111  0.23447642  0.01220059 -0.32294046  2.79379941

g<-ggplot(aes(x = Index, y = Value), data = fortify(x, melt = TRUE))

请问data = fortify(x, melt = TRUE)是什么意思？