R: plotly multiple args in updatemenus with same lable - r

Question

I am somewhat new to plotly and I am trying to make an before-after dot plot in which you can switch variables by dropdown menu. I actually achieved this, but I want to have a color legend feature that categorizes the direction of the before-after differences into "Before > After", "Before < After" etc. In the example I named this variable dir_y. The updatemenus updates the variables (in my example y and z) but I dont know how to update dir_y and dir_z while maintaining only the 2 dropdown options ("Var y" and "Var z"). Needless to say, I need to update dir_y and dir_z in oder to select only one category ("Before > After", "Before < After" etc) from the legend and that category needs to correspond to either y or z depending on which one is selected from the dropdown. I added 2 comments where I thought dir_y and dir_z updating should go, but nothing I tried worked.
Thank you. Any help is greatly appreciated.
Here is my code:
library(plotly)
library(tidyverse)
set.seed(81)
df <- data.frame(id = rep(1:100, 2),
x = c(rep("pre", 100), rep("post", 100)),
y = runif(200),
z = rnorm(200, mean = 50, sd = 10))
df <- df[-sample(1:nrow(df), size = 20) , ] # delete some rows at random to simulate missing values
df_plotly <-
df %>%
mutate(x = forcats::fct_relevel(x, "pre", "post")) %>% # relevel Pre Post for plot
mutate(jit_x = jitter(as.numeric(x))) %>% # add jitter to x discrete var before piping to plotly
mutate(y = round(y, 2),
z = round(z, 2)) %>% # round y & z
group_by(id) %>% # group by id
mutate(dif_y = coalesce(lag(y) - y, y - lead(y)), # do Pre - Post by id for y
dif_z = coalesce(lag(z) - z, z - lead(z))) %>% # do Pre - Post by id for z
mutate(dir_y = case_when(dif_y != 0 && dif_y > 0 ~ "Pre > Post",
dif_y != 0 && dif_y < 0 ~ "Pre < Post",
dif_y == 0 ~ "Pre = Post",
TRUE ~ "Unpaired"),
dir_z = case_when(dif_z != 0 && dif_z > 0 ~ "Pre > Post",
dif_z != 0 && dif_z < 0 ~ "Pre < Post",
dif_z == 0 ~ "Pre = Post",
TRUE ~ "Unpaired"))
p1 <-
df_plotly %>%
plot_ly(x = ~jit_x, y = ~y) %>%
add_trace(x = ~jit_x, y = ~y, color = ~dir_y, colors = c("red", "lightgrey", "green", "black"),
mode = 'markers+lines', type = 'scatter', hoverinfo = 'text+y',
text = ~paste("ID: ", id, "<br>")
) %>%
layout(
title = "",
xaxis = list(title = "",
tickvals = list(1, 2), # jitter(1:2) from 2 levels factor produces values around 1 & 2, should be fine
ticktext = list("Pre", "Post") ),
yaxis = list(title = "",
hoverformat = '.2f',
zeroline = F),
updatemenus = list(
list(
buttons = list(
list(method = "restyle",
args = list("y", list(df_plotly$y) # , "dir_y", list(df_plotly$dir_y)
),
label = "Var Y"),
list(method = "restyle",
args = list("y", list(df_plotly$z) # , "dir_y", list(df_plotly$dir_z)
),
label = "Var Z")))
))
p1