Is there a way to add a horizontal line to a plotly bargraph that is using the cross-talk package?

[davidseg1997]

I am trying to add a horizontal line to each state based on each state's unique Murder rate. Here is my attempted code. Unfortunately, I am not open to using other functions like Shiny because essentially I would like to create an html output from R markdown for my job

Here is my code.Essentially,I created a drop-down select menu so when you select on each state, the Assault, UrbanPop, Rape, and Murder values would automatically change based on the state selected.

At the moment, I created a horizontal line using the murder rate of Alabama (13.2) but I would like to create one based on each state ( ex: Alaska, Murder = 10).

I am also having trouble aligning the text to the top of the line on the right. Any help would be appreciated!

library(tidyverse)
library(reshape2)
library(plotly)
library(crosstalk)

data("USArrests")
     
arrests = rownames_to_column(USArrests, var = "state")

alabama <- arrests %>% filter(state == "Alabama")

arrests <- melt(arrests, id.vars=c("state"))


arrests <- arrests[order(arrests$value),]
# Round 'value' field to 1 decimal
arrests <- arrests %>% mutate(value = round(value, 1))


sd1 <- SharedData$new(arrests, key = ~ state)

hline <- function(y = 0, color = "black") {
  list(
    type = "line",
    x0 = 0,
    x1 = 1,
    xref = "paper",
    y0 = y,
    y1 = y,
    line = list(color = color),
    text = "12"
  )
}

bscols(
  widths = 7, 
  
   filter_select("state",  ## this is the name of column we want to select. 
                "State:", # this is what we want to see in the selection menu
                sd1,
                ~ state, multiple = FALSE),

 plot_ly(sd1) %>%
      add_trace(x = ~ variable, y = ~ value, type = "bar", color = I("yellow"), 
                marker = list(line = list(color = "black", width =1)) ## add order t
                ) %>%
    
    
     layout(barmode = "stack",
             xaxis = list(title = 'Column',
                          tickangle=-45,
                          categoryorder = "total descending"),
            
            yaxis = list(title = ''),
            
            
             width = 600,
            paper_bgcolor = "#FFFFFF",
             plot_bgcolor = "#FFFFFF",
            
            font = list(
              family = "Rubik",
              size = 12,
              color = '#8E8C8F'
             ),
            
            hoverlabel = list(align = "right"),
            
            
            
            shapes = list(hline(alabama$Murder))
            )
  %>% add_text(
    showlegend = FALSE, x = 0,  y = alabama$Murder,
            text = paste0("Murder Rate: ",round(alabama$Murder, 1))
  )
            
)