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Animated plotly gauge plot with changing colors and text annotation

I have a gauge plot I want to animate (following this tutorial), with the color of the plot changing according to the current value. I also want an annotation* which displays the current value of the gauge (I don’t want the standard value displayed in the sector).

I currently have the following:

library(plotly)
library(RColorBrewer)

riskToHex <- function(x) {
  x <- colorRamp(rev(brewer.pal(11, "RdYlBu")))(x / 100)
  rgb <- paste(x[,1], x[,2], x[,3], sep = ",")
  paste0("rgb(", rgb, ")")
}

dd <- data.frame(values = c(90, 60, 20))

dd <- dd %>%
  mutate(colors = riskToHex(dd$values),
         frame = seq.int(nrow(dd)))
dd <- merge(dd, data.frame(values = 200 - dd$values,
                           colors = "white",
                           frame = dd$frame),
            all = TRUE) %>%
  arrange(frame)

plot_ly() %>%
  add_pie(values = dd$values,
          frame = dd$frame,
          rotation = -90,
          marker = list(colors = dd$colors),
          textinfo = "none",
          title = list(text = "Risk score",
                       font = list(size = 20)),
          hoverinfo = "skip",
          sort = FALSE,
          showlegend = FALSE,
          order = "clockwise",
          hole = 0.6) %>%
  add_markers(x = 0,
             y = c(0, 1),
             color = 'rgba(0,0,0,1)') %>%
  add_text(x = 0,
           y = 0.6,
           yshift = 100,
           text = filter(dd, colors != "white")$values,
           frame = distinct(dd, frame)[[1]],
           showlegend = FALSE,
           textfont = list(size = 20)) %>%
  animation_opts(frame = 500) %>%
  layout(
    xaxis = list(showgrid = FALSE,
                 zeroline = FALSE,
                 showticklabels = FALSE
                 ),
    yaxis = list(showgrid = FALSE,
                 zeroline = FALSE,
                 showticklabels = FALSE
    )
  )

This is rather messy and very hacky. I had to use add_text() because I couldn’t figure out how to get annotations to work in this case with changing values in each frame (whether through add_annotations or layout(annotations = ...) ). Unfortunately, the add_text() forced me to add the layout block disabling the axes (which otherwise start to appear). And since the pie chart is seemingly printed on paper space, I also had to add two invisible points so that I could actually position the text (otherwise the axes would always keep the text centered).

Regardless, this successfully generates an animated chart. However, the color only seems to change to the correct value on the following frame (by which time it’s too late). I don’t believe it’s just a processing delay or whatever because accelerating the animation speeds up the color changes as well.

Interestingly, this only happens due to the add_text() block. If I comment that out, the colors on the bar work correctly.

enter image description here

Is there any explanation and solution to this?


For the record, this question was also posted on StackOverflow.


  • I’m open to other solutions!
1 Like

@Wasabi , did you solve this eventually? I would also be interested to know.