I have a data frame containing multiple time series of returns, stored in columns.

The first column contains dates, and subsequent columns are independent time series each with a name. The column headers are the variable names.

## I have a data frame like this
t <- seq(as.Date('2009-01-01'),by='days',length=10)
X <- rnorm(10,0,1)
Y <- rnorm(10,0,2)
Z <- rnorm(10,0,4)

dat <- data.frame(t,X,Y,Z)

## which appears as
           t          X          Y         Z
1 2009-01-01 -1.8763317 -0.1885183 -6.655663
2 2009-01-02 -1.3566227 -2.1851226 -3.863576
3 2009-01-03 -1.3447188  2.4180249 -1.543931

I want to plot each time series as a line on a separate plot, in a lattice, with each plot labeled by the variable names.

To plot this with lattice, the data must be in a tall format, as such: 

           t symbol       price
1 2009-01-01      X -1.8763317
2 2009-01-02      Y -0.1885183
2 2009-01-02      Z -6.655663

What is a good function call to do this?

r time-series
Edit
Report