Modify marker size in legend?

plotly.js
1

Hi there,

I have a quick and simple question which I couldn’t figure out myself.

Is there a way to modify how the legend displays the markers?
At the moment I am using scattergl with thousands of small points per trace…so I had to set the marker size small, which looks nice within the scatter plot but not in the legends where the markers colors are not distinguishable.

Similar thing: I wanted to color my points, using one color for the filling and one for the outline (the outline would indicate the point’s trace and is hence the only color I would like to display in the legend which displays the scatter traces. Does that work?

I would appreciate your help.
Cheers,
Lisa

3 Likes
2

Not at the moment unfortunately.

3

Hello,
I’m picking up that topic again, as one thing crossed my mind so I was playing around but no success yet.

Note that I am using the scattergl plot type.
I am wondering if there is a way to use the legendgroup behavior to accomplish different marker styles in my legend?
I tried creating my regular traces as scattergl plus additional “fake traces” in “box” type, which look nice in the legend, linked using the same legendgroup.
I thought by doing so, I could somehow use the box layout in the legend, while my scatter cointains the scattergl traces.
However, it always screws up my axes.

image
image.png661×523 5.44 KB

Am I missing something or is it just not possible?
Best regards,
Lisa

4

That’s another gl2d limitation. You can’t currently mixed gl2d traces with regular cartesian traces (e.g. box trace). So yeah, that probably messed up the axes.

5

By the way @silly_lily, you might want to subscribe to https://github.com/plotly/plotly.js/pull/1869 for the latest info on our gl2d rewrite. We’re hoping to bring scattergl and gl2d axes to par with cartesian at some point this fall.

1 Like
6

Hi,

was there any improvements in that direction?

Thanks

7

Still no way to set a legend marker size in Plotly… imagine a scatter plot with 5000 points…
either giant markers in the plot, or microscopic legend dots… Is there still no simple solution for this? I simple legend(markersize = x) argument sounds so simple to add.

p.s. i’m using plotly in R

2 Likes
8

Hi !
Have you found something ?
I have the same issue in Python.
Best

9

I have found a very ugly work around

library(plotly)
library(shiny)
library(htmlwidgets)
library(colourpicker)


ui <- fluidPage(
  fluidRow(
     column(8,
           plotlyOutput("plot1")
    ),
    column(2,
                   colourpicker::colourInput(inputId = 'markercolor', label = 'X',
           palette = "limited", 
           showColour = "background", returnName = TRUE),
           selectInput(inputId = 'traceNo', label = 'Trace', choices = c(1:3), selected = 1),
           br(),
           h5('Switch'),
           actionButton(inputId = 'Switch', label = icon('refresh'), style = "color: #f7ad6e;   background-color: white;  border-color: #f7ad6e;
                        height: 40px; width: 40px; border-radius: 6px;  border-width: 2px; text-align: center;  line-height: 50%; padding: 0px; display:block; margin: 2px")
    )
  )
)

server <- function(input, output, session) {
  # values <- reactiveValues()


  observeEvent(input$Switch, { 
    plotlyProxy("plot1", session) %>%
      plotlyProxyInvoke("restyle", list(marker = list(color = input$markercolor)), list(as.numeric(input$traceNo)-1))
    })

  output$plot1 <- renderPlotly({
    markersize <- 4
    markerlegendsize <- 20
   colors <- c('red', 'blue', 'black')
    p1 <- plot_ly()
    p1 <-  add_trace(p1, data = mtcars, x = ~disp, y = ~mpg, type = 'scatter', mode = 'markers', color = ~as.factor(cyl), colors = colors)
    p1 <- layout(p1, title = 'mtcars group by cyl with switching colors')
    p1 <- plotly_build(p1)

    ## this is a bit of a hack to change the size of the legend markers to not be equal to the plot marker size. 
    ## it makes a list of 1 size value for each marker in de trace in the plot, and another half of with sizes that are a lot bigger.
    ## the legend marker size is effectively the average size of all markers of a trace
    for(i in seq(1, length(sort(unique(mtcars$cyl) )))) {
      length.group <- nrow(mtcars[which(mtcars$cyl  == sort(unique(mtcars$cyl))[i]), ])
      p1$x$data[[i]]$marker$size <- c(rep(markersize,length.group), rep(c(-markersize+2*markerlegendsize), length.group))
    }
    p1
  })
}

shinyApp(ui, server)
10

Thank you! I’ll try this way.

11

any update ? this lack of capability is keeping our team from switching from bokeh to plotly :frowning:

2 Likes
12

I’ve run into this issue many times too. A fix would be fantastic.

13

Also had problem with scatters of small markers leading to tiny legend. I found workaround:

fig.update_layout(legend= {'itemsizing': 'constant'})

from here:

It makes the size of the legend independent of the marker size.
Solves the underlying problem many seem to have, but not the one OP asked about.

4 Likes
14

Made an account just to say thank you so much.

You saved me.

edit: idk if this is clear or not but anbjork’s solution works.

If you’re doing this in r just do layout(legend = list(itemsizing = “constant”))

1 Like