Subplot grouped legend for grouped bar charts

Question

I am trying to add a subplot grouped legend to series of GROUPED bar charts in plotly. I've found numerous examples of subplot grouped legends for charts generally (like the last graphical example here: https://plot.ly/r/legend/), but I cannot get the "legendgroup = ~" method to work for GROUPED bar charts.

I have survey data from two different years (2017 and 2019) for a number of operating units at my company. I want to show the 2017 and 2019 survey results side-by-side for each operating unit individually in a grouped bar format with a chart for each operating unit. The only element that is not working is the legend for the survey year (2017 or 2019) which I want to work across all the graphs.

library(data.table)
library(plotly)

# Dummy data 
data <- data.table(Group = rep(c("Business_Unit_1","Business_Unit_2"), each = 4),
                   Question = rep(c("Happy","Ethics","Happy", "Ethics"), each = 2),
                   Year = c("2017", "2019", "2017", "2019", "2017", "2019", "2017", "2019"),
                   Prop = c(.9, .95, .8, .75, .7, .8, .8, .97))

# Grouped bar chart 1                    
plot_1 <- plot_ly() %>%
  add_trace(x = ~ data[Group == "Business_Unit_1" & Year == "2017", (Question)],
            y = ~ data[Group == "Business_Unit_1" & Year == "2017", (Prop)],
            name = "2017",
            type = 'bar',
            marker = list(color = 'rgb(158,202,225)',
                          line = list(color = 'rgb(8,48,107)', width = 1.5))) %>%
  add_trace(x = ~ data[Group == "Business_Unit_1" & Year == "2019", (Question)],
            y = ~ data[Group == "Business_Unit_1" & Year == "2019", (Prop)],
            name = "2019",
            type = 'bar',
            marker = list(color = 'rgb(58,200,225)',
                          line = list(color = 'rgb(8,48,107)', width = 1.5))) %>%
  layout(yaxis = list(title = 'Proportion'),
         annotations = list(x = 0.5 , y = 1.05, text = "Business_Unit_1", showarrow = F, xref = 'paper', yref = 'paper'),
         barmode = 'group')

# Grouped bar chart 2
# Right now I am just hiding the second legend
plot_2 <- plot_ly() %>%
  add_trace(x = ~ data[Group == "Business_Unit_2" & Year == "2017", (Question)],
            y = ~ data[Group == "Business_Unit_2" & Year == "2017", (Prop)],
            name = "2017",
            type = 'bar',
            showlegend = FALSE,
            marker = list(color = 'rgb(158,202,225)',
                          line = list(color = 'rgb(8,48,107)', width = 1.5))) %>%
  add_trace(x = ~ data[Group == "Business_Unit_2" & Year == "2019", (Question)],
            y = ~ data[Group == "Business_Unit_2" & Year == "2019", (Prop)],
            name = "2019",
            type = 'bar',
            showlegend = FALSE,
            marker = list(color = 'rgb(58,200,225)',
                          line = list(color = 'rgb(8,48,107)', width = 1.5))) %>%
  layout(yaxis = list(title = 'Proportion'),
         annotations = list(x = 0.5 , y = 1.05, text = "Business_Unit_2", showarrow = F, xref = 'paper', yref = 'paper'),
         barmode = 'group')

# Create the subplot
plots <- subplot(plot_1, plot_2, shareY = TRUE, nrows = 1)
plots

The way this code is written, the legend is linked to the first plot only and the second plot's legend is hidden. Could someone please help?

Subplot grouped legend for grouped bar charts

Answers (1)

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