Color surface by variable with plotly in R

Question

Using the volcano data, I would like to color the surface of the volcano by another variable, which is a matrix, MatrixForColor, of the same size as volcano and it only contains 1s and 2s (is binary). For MatrixForColor = 1 and MatrixForColor = 2 I want to color blue and red, respectively.

Inspired from Formatting of persp3d plot, I managed to achieve this using persp3d from rgl package as following:

library(rgl)    
color = c("blue", "red")
type  = MatrixForColor
persp3d(volcano, theta=50, phi=25, expand=0.75, col=color[type],
        ticktype="detailed", xlab="", ylab="", zlab="", axes=TRUE)

and obtained this figure:

I also tried to achieve this with plotly (adapting after the response from plotly - different colours for different surfaces) as following:

library(plotly)
plot_ly(colors = c('blue', 'red')) %>%
  add_surface(z = volcano,
              opacity = 0.8,
              surfacecolor=MatrixForColor,
              cauto=F,
              cmax=1,
              cmin=0
  )

but I get this figure:

which is not what I want, since it's not colored as red and blue after MatrixForColor.

Any has any idea how to do this with plotly?

Can you also include `MatrixForColor` ? – SeGa Jun 11 '19 at 07:58 — SeGa, Jun 11 '19 at 07:58

score 2 · Accepted Answer · answered Jun 11 '19 at 08:00

You will need to set correct values for cmin and cmax:

library(plotly)

MatrixForColor <- matrix(1, nrow = nrow(volcano), ncol = ncol(volcano))
MatrixForColor[, 1:30] <- 2

plot_ly(colors = c('blue', 'red')) %>%
  add_surface(z = volcano,
              opacity = 0.8,
              surfacecolor = MatrixForColor,
              cauto=F,
              cmax=max(MatrixForColor),
              cmin=min(MatrixForColor)
  )

Color surface by variable with plotly in R

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