drawing rectangle on plotly R

Question

I would like to draw a rectangle polygon over a plotly plot that uses dates. As a toy example my code is

library(tidyverse)
library(plotly)

df <- tibble(daydate = dmy(c("01-01-2022", "01-02-2022", "15-02-2022", "27-02-2022")),
       value = runif(4, 0, 100))

plot_ly(df, x = ~daydate, y = ~value, color = I("#9B4393"), type = 'scatter', mode = 'lines')  

I would like to draw a rectangle that spans the dates "01-02-2022" to "15-02-2022", and from 0 to 100. Also, I would like to have the rectangular area grey colour that is quite transparent.

Many thanks

Answer 1

Define a rectangle:

my_rectangle <- list(
    type = "rect",
    fillcolor = "grey",
    line = list(color = "black"),
    opacity = 0.3,
    x0 = "2022-02-01",
    x1 = "2022-02-15",
    xref = "x",
    y0 = 0,
    y1 = 100,
    yref = "y"
)

Add it to the plot:

plot_ly(
    df,
    x = ~daydate,
    y = ~value,
    color = I("#9B4393"),
    type = "scatter",
    mode = "lines"
) |>
    layout(
        shapes = list(
            my_rectangle
        )
    )

The R plotly documentation sets out how you can draw and style rectangles and various other shapes.