How to draw multiple 2d-plots in a 3d-plot in R?

Question

I am not sure if I formulated the title/question correct. Maybe one of my problems are missing terms in my vocabulary. Sorry. But lets try:

I have data (sleep in this example) I would describe as three-dimensional. Maybe a real statistican wouldn't do that?

I think I want to draw multiple two-dimensional plots into a three-dimensial one. I want to plot them side by side. Please correct me if I am wrong.

My problem here is that there is only one line. There are two groups. I want one line per group. The same data with type='h' give a better description I think:

Can you imagine the two lines here? What I am missing in that concept? We could use another ploting library for printing/publication. Currently it doesn't matter for me which one. Maybe I am totaly at the wrong place?

This is the code:

require('mise')
require('scatterplot3d')
mise()  # clear the workspace

# example data
print(sleep)

scatterplot3d(x=sleep$ID,
              x.ticklabs=levels(sleep$ID),
              y=sleep$group,
              y.ticklabs=levels(sleep$group),
              lab = c(length(unique(sleep$ID)), 1),
              z=sleep$extra,
              type='o')

And the data

   extra group ID
1    0.7     1  1
2   -1.6     1  2
3   -0.2     1  3
4   -1.2     1  4
5   -0.1     1  5
6    3.4     1  6
7    3.7     1  7
8    0.8     1  8
9    0.0     1  9
10   2.0     1 10
11   1.9     2  1
12   0.8     2  2
13   1.1     2  3
14   0.1     2  4
15  -0.1     2  5
16   4.4     2  6
17   5.5     2  7
18   1.6     2  8
19   4.6     2  9
20   3.4     2 10

Answer 1

You could add the lines manually in two steps:

# Store the plot in rr
rr <- scatterplot3d(x=as.numeric(sleep$ID),
                    x.ticklabs=levels(sleep$ID),
                     y=sleep$group,
                     y.ticklabs=levels(sleep$group),
                     z=sleep$extra)
# find all that belong to group one
idx = sleep$group == 1
# add the first line
rr$points3d(x = sleep$ID[idx], y = rep(1, each = sum(idx)), z = sleep$extra[idx], type = 'l', col = 'red')
# add the second line
rr$points3d(x = sleep$ID[!idx], y = rep(2, each = sum(!idx)), z = sleep$extra[!idx], type = 'l', col = 'blue')

So to add ribbons instead of lines things change a bit. In particular, the ribbons are plotted with the polygon function. However, this function only handles 2D coordinates, so we need to transform our 3D coordinates to 2D coordinates with the function rr$xyz.convert.

rr <- scatterplot3d(x=sleep$ID,
                    x.ticklabs=levels(sleep$ID),
                     y=sleep$group,
                     y.ticklabs=levels(sleep$group),
                     z=sleep$extra)
idx = sleep$group == 1
# draw first group
mat = matrix(c(rep(sleep$ID[idx], 2),
               rep(c(1, 1.05), each = sum(idx)), # 1.05 determines width
               rep(sleep$extra[idx], 2)), ncol = 3)
ll = rr$xyz.convert(mat)
polygon(x = ll$x[c(1:10, 20:11)], 
        y = ll$y[c(1:10, 20:11)], col = 'red')
# draw second group
mat = matrix(c(rep(sleep$ID[!idx], 2),
               rep(c(2, 1.95), each = sum(!idx)), # 1.95 determines width
               rep(sleep$extra[!idx], 2)), ncol = 3)
ll = rr$xyz.convert(mat)
polygon(x = ll$x[c(1:10, 20:11)], 
        y = ll$y[c(1:10, 20:11)], col = 'blue')