ColorScale Will Not Change If Specifying with colorscale = c('hexcode1', 'hexcode2')

[OhStan]

Hi,

After following the guide here, https://plotly.com/r/3d-scatter-plots/, I found that, when specifying color scale with colorscale = c('hexcode1', 'hexcode2') will not have changes to the color scale, yet the default palette names such as 'Rainbow' will work. In this case, it would not be possible to self-define the 2 end points of the color scale. Please feel free to run the R codes below to see what I mean.

library(dplyr)
library(plotly)

fig <- plot_ly(mtcars, x = ~wt, y = ~hp, z = ~qsec,
               marker = list(color = ~mpg, 
                             #colorscale = c('#FF0000', '#00FF72'), 
                             #colorscale ='Rainbow',
                             colorscale = c('#132B43', '#56B1F7'),
                             showscale = TRUE))
fig <- fig %>% add_markers()
fig <- fig %>% layout(scene = list(xaxis = list(title = 'Weight'),
                                   yaxis = list(title = 'Gross horsepower'),
                                   zaxis = list(title = '1/4 mile time')),
                      annotations = list(
                        x = 1.13,
                        y = 1.05,
                        text = 'Miles/(US) gallon',
                        xref = 'paper',
                        yref = 'paper',
                        showarrow = FALSE
                      ))
fig

Just wondering if this is a bug or may be there needs some updates to the guide?

Thanks,

[yogat3ch]

Hi @cpsievert,
I'm wondering if there's been any progress on ensuring the colorscale argument to plot_ly and/or add_markers/trace is passed through to the plotly.js library?

Another reprex:

plotly::plot_ly(mtcars, x = ~ wt, y = ~ hp) |>
          plotly::add_markers(color = ~ mpg,
                              marker = list(colorscale = c("black", "red")))

Formatted differently, it appears to apply the color gradient to the markers, but the colorbar doesn't update:

 plotly::plot_ly(mtcars, x = ~ wt, y = ~ hp) |>
          plotly::add_markers(color = ~ mpg,
                              marker = list(colorscale = list(c(0,1), c("black", "red"))))

Using an array:

plotly::plot_ly(mtcars, x = ~ wt, y = ~ hp) |>
          plotly::add_markers(color = ~ mpg,
                              marker = list(colorscale = list(
                                c(0, 0.2, 0.4, 0.6, 0.8, 1),
                                c(
                                  "#FFB7B2",
                                  "#EA9C95",
                                  "#D68279",
                                  "#C2675C",
                                  "#AE4D40",
                                  "#9A3324"
                                )
                              )))

1. It looks like the color spectrum is reversed, with the 1 (100th) percentile, corresponding to the lightest color rather than the darkest color.
2. The colorbar does not update to reflect the values of the colorscale

Are these issues in the plotly R library or in plotly js?

[JElchison]

I think the issue may be that marker is the incorrect container for the color specs? Also, colors is not the same as colorscale.

Try this:

library(dplyr)
library(plotly)

fig <- plot_ly(mtcars, x = ~wt, y = ~hp, z = ~qsec,
               color = ~ mpg,
               colors = c('#132B43', '#56B1F7'))
fig <- fig %>% add_markers()
fig <- fig %>% layout(scene = list(xaxis = list(title = 'Weight'),
                                   yaxis = list(title = 'Gross horsepower'),
                                   zaxis = list(title = '1/4 mile time')),
                      annotations = list(
                        x = 1.13,
                        y = 1.05,
                        text = 'Miles/(US) gallon',
                        xref = 'paper',
                        yref = 'paper',
                        showarrow = FALSE
                      ))
fig

IMHO the real issue is the incorrect example at https://plotly.com/r/3d-scatter-plots/#3d-scatter-plot-with-color-scaling

It should be:

library(plotly)

fig <- plot_ly(mtcars, x = ~wt, y = ~hp, z = ~qsec,
               color = ~mpg,
               colors = c('#FFE1A1', '#683531'))
fig <- fig %>% add_markers()
fig <- fig %>% layout(scene = list(xaxis = list(title = 'Weight'),
                                   yaxis = list(title = 'Gross horsepower'),
                                   zaxis = list(title = '1/4 mile time')),
                      annotations = list(
                        x = 1.13,
                        y = 1.05,
                        text = 'Miles/(US) gallon',
                        xref = 'paper',
                        yref = 'paper',
                        showarrow = FALSE
                      ))
fig