[R] Matrix as input to xyplot {lattice} - proper extended formula syntax

[David Winsemius]

I'm not exactly sure what structure df has. Here's my effort to  
duplicate it:

df <- data.frame(y=matrix(rnorm(24), nrow=6), x=1:6)
 > df
          y.1        y.2        y.3        y.4 x
1  0.1734636  0.2348417 -1.2375648 -1.3246439 1
2  1.9551669 -1.1027262 -0.7307332  0.3953752 2
3 -0.7645778  1.6297861  0.4743805 -0.4476145 3
4 -0.5308756 -0.5246534 -0.3854609 -1.6097777 4
5  0.7406525 -0.8691720 -0.8194084  1.6122059 5
6 -0.9625619 -1.0774165  1.0760829  0.3659436 6

And this seems to accomplish the desired task. Presumably you have  
assigned off-stage the value of title to a meaningful character string?

 > p <- xyplot(y.1+y.2+y.3+y.4 ~ x |1:4, data = df, main =  
"title" ,layout=c(1,4) )
 > p




On Sep 5, 2009, at 11:52 PM, Bryan Hanson wrote:

> Hello R Folks...
>
> I have a list with the following structure:
>
>> str(df)
> List of 3
> $ y    : num [1:4, 1:1242] -0.005379 0.029874 -0.023274 0.000655  
> -0.004537
> ..
> $ x    : num [1:1242] 501 503 505 507 509 ...
> $ names: Factor w/ 4 levels "PC Loading 1",..: 1 2 3 4
>
> I want to plot each row of df$y against df$x, and have each plot in  
> it’s own
> panel according to the levels of df$names.  The following works in  
> the sense
> that the layout is right, but the y values have clearly been  
> recycled or
> skipped in some fashion (and an error is thrown for each panel that  
> the
> length of x and y aren’t the same):
>
> p <- xyplot(y ~ x | names, data = df, main = title,
>        layout = c(1, dim(y)[1])
>
> In reviewing the extended formula interface in the Lattice Book,  
> what I want
> to happen is y1 + y2 + y3 + y4 ~ x | names, outer = TRUE
>
> I see two options: figure out a way to create the extended formula  
> on the
> fly (and the actual number of rows in y may vary), which seems  
> potentially
> tricky, or create a data frame by stacking each row of y and  
> repeating x and
> names to match.  This seems like a waste of memory.
>
> I’ve looked through the archives and haven’t come across something  
> quite
> like this, or at least I don’t recognize it if I have!  Is there a  
> more
> elegant way to tell xyplot I want to use each row of y repeatedly  
> with the
> same x, in a loop-like fashion?
>
> TIA.  Bryan
> *************
> Bryan Hanson
> Professor of Chemistry & Biochemistry
> DePauw University, Greencastle IN USA
>
>
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>
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT