My plotly lines are split by the interaction of two groups, and colored by another group. It is working except the legend still show all the interactions, which is unnecessary. I am currently using the code below:
dt%>%
plot_ly(x = ~x.center, y = ~y.center, z = ~z.center, type = 'scatter3d', mode = 'lines+markers', opacity = 1, marker = list(size = 2),
split = ~interaction(spreadsheet_row,participant.id), color = ~tasktype)
Just want the legend to be below (color by tasktype): 
Thanks in advance for help.