Colors per factor-level in plotly - r

Question

A client wants me to make a plot like this. This reference uses the rgl-package, but the quality of the exported figures is too low. Thus, I started in plotly. I can manage most of the things I want to do, but for some reason, all the bars are in different colors.
A MWE:
X<-1:60
Y<-sort(runif(60,-3,3))
Z<-runif(60,0,50)
p<-plot_ly(x = c(X[1],X[1]+1,X[1]+1,X[1]),
y = c(0,0,Y[1],Y[1]), z=c(0,0,0,0),type = "mesh3d",color=I("red"))
for(i in X){p<-add_trace(p,x = c(i,i+1,i+1,i),
y = c(0,0,Y[i],Y[i]), z=c(0,0,0,0),type = "mesh3d",color=I("red"))}
for(i in X){p<-add_trace(p,x = c(i,i+1,i+1,i),
y = c(0,0,0,0), z=c(0,0,Z[i],Z[i]),type = "mesh3d",i=c(0,0),
j=c(1,2),k=c(2,3),color=I("black"))}
p
While I would expect something in red and black, I get this multicolored result:
What I'm actually looking for is something like the following, with a color for each factor level, but for now, the result is identical to the one above:
X<-1:60
Y<-sort(runif(60,-3,3))
Z<-runif(60,0,50)
ColFactor<-sample(c(0,1),60,replace = TRUE)
p<-plot_ly(x = c(X[1],X[1]+1,X[1]+1,X[1]), y = c(0,0,Y[1],Y[1]), z=c(0,0,0,0),
type = "mesh3d",color=ColFactor,colors=c("red","blue"))
for(i in X){p<-add_trace(p,x = c(i,i+1,i+1,i), y = c(0,0,Y[i],Y[i]), z=c(0,0,0,0),
type = "mesh3d",color=ColFactor,colors=c("red","blue"))}
for(i in X){p<-add_trace(p,x = c(i,i+1,i+1,i), y = c(0,0,0,0), z=c(0,0,Z[i],Z[i]),
type = "mesh3d",i=c(0,0),j=c(1,2),k=c(2,3),color=I("black"))}
p

Answer 1

It seems there is some kind of issue when using plot_ly the way you intend to do.
However, there is a workaround (https://github.com/ropensci/plotly/issues/413).
To make things work you have to overriden the default values provided by plot_ly by mean of the plotly_build function.
The following code should work to obtain a plot where horizontal and vertical bars have different color:
X<-1:60
Y<-sort(runif(60,-3,3))
Z<-runif(60,0,50)
ColFactor<-sample(c(0,1),60,replace = TRUE)
p<-plot_ly(color=I("black")) #This plot a layout where to add the traces and adds
#the attribute color needed when overriding default. If it isn't included it doesn't work
#Which color you use here is unimportant, it will be override
#next lines add the bars, if you plot the result will be the same that you already know
for(i in X){p<-add_trace(p,x = c(i,i+1,i+1,i),
y = c(0,0,Y[i],Y[i]), z=c(0,0,0,0),type = "mesh3d")}
for(i in X){p<-add_trace(p,x = c(i,i+1,i+1,i),
y = c(0,0,0,0), z=c(0,0,Z[i],Z[i]),type = "mesh3d",i=c(0,0),
j=c(1,2),k=c(2,3))}
#next step: override the defaults options using plotly_build()
p.optionslist<-plotly_build(p)
#you have to change every trace individually that's what the for loop is
#horizontal bars
for(j in 1:((length(p.optionslist$x$data))/2)){
p.optionslist$x$data[[j]]$color=toRGB("red")
}
#horizontal vertical bars
for(j in (((length(p.optionslist$x$data)/2)+1):length(p.optionslist$x$data))){
p.optionslist$x$data[[j]]$color=toRGB("blue")
}
#The plot
p.optionslist
Regarding the use of a ColFactor the following code works (surely there is a better way but I don't know which one)
#overriding color option according to the value of ColFactor
p.optionslist2<-plotly_build(p)
for(j in 1:((length(p.optionslist2$x$data))/2)){
if(ColFactor[j]==1){
p.optionslist2$x$data[[j]]$color=toRGB("red")
}else{
p.optionslist2$x$data[[j]]$color=toRGB("blue")
}
}
for(j in (((length(p.optionslist2$x$data))/2)+1):length(p.optionslist2$x$data)){
i=j-length(ColFactor)
if(ColFactor[i]==1){
p.optionslist2$x$data[[j]]$color=toRGB("red")
}else{
p.optionslist2$x$data[[j]]$color=toRGB("blue")
}
}
#The plot with color by
p.optionslist2
If you want the vertical bars all in black and the horizontal bars by factor then you only have to combine both options:
p.optionslist3<-plotly_build(p)
for(j in 1:((length(p.optionslist3$x$data))/2)){
if(ColFactor[j]==1){
p.optionslist3$x$data[[j]]$color=toRGB("red")
}else{
p.optionslist3$x$data[[j]]$color=toRGB("blue")
}
}
for(j in (((length(p.optionslist3$x$data))/2)+1):length(p.optionslist3$x$data)){
p.optionslist3$x$data[[j]]$color=toRGB("black")
}
#The plot with color by
p.optionslist3
Hope it helps you!