[R] muliple plots with pairs (matrix of scatter plots)

[Uwe Ligges]

Tiago R Magalhaes wrote:

> I am trying to make a graph with 4 scatter matrixes plots and 
> couldn't do it. While trying to find a solution for this I also came 
> across the idea of giving different values to the same argument for 
> each of the lower and upper function but couldn't do it. (Examplified 
> below with the col argument). The first problem of plotting 4 scatter 
> matrixes in a graph is a problem of real interest for me at this 
> point. The second problem is a matter of curiosity.
> 
> I am using a Mac PowerBook G4 with OS 10.3.7 and R 2.0.1
> 
> 
> Problem 1)
> x=data.frame(a=sample(1:100, 50), b=sample(1:100, 50),c=sample(1:100, 
> 50),d=sample(1:100, 50))
> x.list=vector('list',4)
> for (j in 1:4) x.list[[j]]=x
> 
> #produces a graph with four plots:
> layout(matrix(c(1,3,2,4),2,2))
> for (j in seq(x)){
> 	plot(x.list[[j]][1:2])
> 	}
> 
> # But unfortunately the following produces a new plot everytime:
> layout(matrix(c(1,3,2,4),2,2))
> for (j in seq(x)){
> 	pairs(x.list[[j]])
> 	}
> #Maybe pairs can't be used to produce a graph with multiple plots?

Yes, it uses similar constructs to put multiple plots together.

You might want to use packages grid and gridBase to set something up 
using viewports.


> Problem 2)
> I wanted to plot upper and lower panels with different colours. I 
> tried what I thougth was obvious, giving the col argument inside of 
> each function:
> pairs (x, lower.panel=points(x, col=2), upper.panel=points(x, 
> col=3))# only the diagonal is plotted
> pairs (x, lower.panel=points(x), upper.panel=points(x))  #once again 
> only the diagonal is plotted
> pairs (x, lower.panel=points, upper.panel=points)  #both panels are 
> plotted, actually, this is simlar to pairs(x)
> 
> #Another little observation that I thought was strange:
> pairs(x, lower.panel=points(x), col=2)# colours the outside box red
> pairs(x, lower.panel=points(x), col=2, xaxt='n', yaxt='n')# does what I want
> pairs(x, lower.panel=points(x, col=2))# doesn't change the colour but 
> works otherwise


You have to specify a function, e.g. an unnamed one such as
    function(x, y) points(x, y, col=2)
rather than a function call such as just
    points(x)

Hence we get:

pairs(x, lower.panel = function(x, y) points(x, y, col=2),
          upper.panel = function(x, y) points(x, y, col=3))



Uwe Ligges


> Thank you very much for any comments and help
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