When plotting with plotly in R, how does one specify a color and a symbol based on a value? For example with the mtcars example dataset, how to plot as a red square if mtcars$mpg is greater or less than 18?
For example:
library(plotly)
p <- plot_ly(type = "scatter", data = mtcars, x = rownames(mtcars), y = mtcars$mpg,
mode = "markers" )
How to get all points above 20 as yellow squares?