Re: [R] Creating grid graphics with grid.layout

[Jeff Horner]

Paul Murrell wrote:
Hi
If using integer indices is awkward, you could push a viewport tree with 
the relevant viewports given useful names.  Then you can downViewport() 
using the names (if those plots are lattice plots, then you might even 
be able to use the 'draw.in' argument).  Is that the sort of thing you 
are looking for?

Actually no, integer is just fine, and querying viewports by name would 
be slower, no?. I more wanted to confirm that my approach was sound, 
using lapply and loops, and that I was using as much of the grid 
vectorizing features that were available. For instance, a few iterations 
ago I attempted to construct what I thought was a vector of viewports 
like so:

x <- c(2,4,2,4)
y <- c(2,2,4,4)
print(...,vp=viewport(layout.pos.col=x,layout.pos.row=y)

which would print ... to each viewport. I realize now that specifying a 
vector for layout.pos.* args is just to construct one larger viewport of 
the adjacent viewports, right?

Thanks for the quick feedback!

Jeff

Paul


Jeff Horner wrote:
Hi,

I recently created a function which uses grid with a viewport 
constructed with grid.layout() to position four plots on a plot 
device. My question is what's the best way to programatically traverse 
each element of the viewport?

The grid is 5x5 and the four plots occupy positions (2,2), (4,2), 
(2,4), and (4,4).

Here's the viewport code:

  pushViewport(
         viewport(
             layout=grid.layout(
                 nrow=5,
                 ncol=5,
                 widths=unit(
                     c(margin[2],1,margin[6],1,margin[4]),
                     c('npc','null','npc','null','npc')),
                 heights=unit(
                     c(margin[3],1,margin[5],1,margin[1]),
                     c('npc','null','npc','null','npc'))
             )
         )
     )

margin is a numeric vector of length 6 which resp defines the bottom, 
left, top, right, horizontal, and veritical margins (the cross hairs 
between the 4 plots). This is to allow the user to define how much 
margin should exist around all plots and between the plots.

I then use lapply to visit only those viewports to place the plots by 
specifying an x and y vector like so:

x <- c(2,4,2,4)
y <- c(2,2,4,4)
i <- 1
lapply(list(plot1,plot2,plot3,plot4),function(j){
    print(j,vp=viewport(layout.pos.col=x[i],layout.pos.row=y[i])
    i <<- i + 1
})

Looks kludgey. Is there a better way?

Also, I created debug code to visit those viewports where *nothing* is 
supposed to be printed except for a grey box with black edges:

z <- outer(logical(5),logical(5),"==")
for (i in 1:length(x)) z[x[i],y[i]] <- FALSE
for (i in 1:5){
    for (j in 1:5){
       if (z[i,j])
          grid.rect(gp=gpar(fill="grey"),
            vp=viewport(layout.pos.col=i,layout.pos.row=j))
    }
}

This looks kludgey as well. Any other ways outer there that are more 
elegant?

Thanks,

Jeff

______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide 
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.


______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.