Overlay a grouped bar chart with scatter in plotly

Question

I'm trying to superimpose a scatter on top of a grouped bar chart in plotly. However, whereas in a simple bar chart the scatter points are correctly placed at the top of the respective bars, in a grouped bar chart the scatter points do not automatically adjust.

Here is an example demonstrating the problem:

set.seed(1)
d1 <- data.frame(x=rep(c('a', 'b', 'c'), each=2),
                 y=rnorm(6, mean=10),
                 c=rep(c('q', 'r'), times=3))
d2 <- d1[d1$c=='q', ]

p1 <- plot_ly(data=d2, x=~x, y=~y, type='bar')
p2 <- add_trace(p1, data=d2, x=~x, y=~y, 
                type='scatter', mode='markers', marker=list(size=20))
p3 <- plot_ly(data=d1, x=~x, y=~y, color=~c, type='bar')
p4 <- add_trace(p3, data=d1, x=~x, y=~y, 
                type='scatter', mode='markers', marker=list(size=20))

subplot(p1, p2, p3, p4, nrows=2)

This generates the following figure:

Whereas in the top right panel (p2) the points are placed at their respective bars, in the bottom right (p4), the points do not adjust to the colour factor.

I can imagine solving this problem by setting x as a numeric variable and manually, adjusting the points by a small amount, etc. But this seems rather tedious. Is there a simple way to make plotly do the adjustment?

(Obviously the goal is not to have a single point showing the top of each bar, but overlay the bars with a whole cloud)

vlizana vlizana · Accepted Answer · 2019-02-09T06:01:53

Depends on what you're trying to do you you can use error bars, you can play with the width, thickness and color parameters to make it look like a regular scatter (width refers to the line at the ends and thickness to the whiskers, thickness = 0 should take them out).

Overlay a grouped bar chart with scatter in plotly

1 Answers