Adam Laiacano

Colored plotmatrix in ggplot2

I feel like plotmatrix is a much-neglected ggplot2 function (it’s not even on the ggplot2 webpage). It’s the equivalent of plot(dataframe) from the core graphics package, with the added bonus of a kernel density plot along the diagonal.

The one thing that seems to be missing is the ability to color the points by some factor. I modified the plotmatrix function to enable this. Here’s an example.

My data looks something like this:

> head(data)
   a  b  c  d level
1  1  2  5  2 FALSE
2  1 21  2  1 FALSE
3 26  1 NA  1 FALSE
4  8 45 13 12 FALSE
5  3 25  4  4 FALSE
6  4 NA  1  2 FALSE

And when I plot it using plotmatrix I get the following:

plotmatrix(data, mapping=aes(colour=data$level))

None of the aesthetic mappings actually make it to the plot.  I changed it so that the aesthetics get passed to the points only:

plotmatrix2(data, mapping=aes(colour=data$level, shape=data$level))

And here’s the code: