Plotly legendgroup for subplots so a single legend controls all charts - r

Question

I'm using plotly in r to generate a number of subplots. A toy example is shown below.
library(shiny)
library(dplyr)
library(plotly)
## Toy Example
ui <- fluidPage(
h3("Diamonds"),
plotlyOutput("plot", height = 600)
)
server <- function(input, output, session) {
# reduce down the dataset to make the example simpler
dat <- diamonds %>%
filter(clarity %in% c("I1", "IF")) %>%
mutate(clarity = factor(clarity, levels = c("I1", "IF")))
output$plot <- renderPlotly({
# Generates the chart for a single clarity
byClarity <- function(df){
Clarity <- df$clarity[1];
plot_ly(df, x = ~carat, y = ~price, color = ~cut, name = ~clarity) %>%
add_trace(
type="bar"
## Also tried adding this with no success
# legendgroup = ~cut
) %>%
layout(
barmode = "stack"
)
}
dat %>%
split(.$clarity) %>%
lapply(byClarity) %>%
subplot(nrows = NROW(.), shareX = TRUE, which_layout = "merge")
})
}
shinyApp(ui, server)
I would like to make the legends such that clicking on a 'Cut' on the legend will show/hide that 'Cut' from both charts instead of just the chart associated with that legend.
I looked at legendgroup but can't figure out how to associate it with cut instead of clarity (clarity is the grouping I'm using to make the subplots).
I also need the solution to work with raw plot_ly and not ggplotly as there are other plot_ly functionalities I need that aren't available in ggplotly.
Any help would be appreciated. I am using plotly_4.5.2, dplyr_0.5.0, and shiny_0.14.

Answer 1

Ok, here is a solution using ggplot2:
library(ggplot2)
library(dplyr)
library(plotly)
dat <- diamonds %>%
filter(clarity %in% c("I1", "IF")) %>%
mutate(clarity = factor(clarity, levels = c("I1", "IF")))
# Function for nice labels
k_label <- function(x) {
c(0, paste0((x)/1000,"K")[-1])
}
# ggplot
p <- ggplot(dat,aes(x=carat, y=price, fill=cut)) +
geom_bar(stat="identity") +
facet_wrap(~clarity,nrow=2, scales = "free_y") +
scale_y_continuous(labels = k_label) +
theme_minimal() + ylab("") + xlab("") +
theme(legend.title=element_blank(),
panel.grid.major.x=element_blank())
# a plotly
ggplotly(p)

Answer 2

Try adding legendgroup = ~cut to both traces and setting showlegend = F for one of them. Then in layout set showlegend = T
Like this:
plot_ly(df, x = ~carat, y = ~price, color = ~cut, name = ~clarity, legendgroup = ~cut, showlegend = T) %>%
add_trace( type="bar", legendgroup = ~cut, showlegend = F) %>%
layout(
barmode = "stack",showlegend = T
)