Highcharter annotation on date x-axis not working - R

Question

I am trying to add annotation for my highcharter chart, not sure why it is not working, instead it is showing [object][object].

Here is my data,

structure(list(variable = structure(c(15522, 15553, 15584, 15614, 
15645, 15675, 15706, 15737, 15765, 15796), class = "Date"), value = c(417376, 
423563, 430290, 455643, 451542, 422419, 429472, 451694, 454900, 
456844)), row.names = c(NA, 10L), .Names = c("variable", "value"
), class = "data.frame")

Code, I am trying to add annotation only for last value in the graph, may be in a rectangle box.

currmonth <- max(pricedata$variable)
pricedata$value <- round(pricedata$value)
highchart(type = "chart") %>% 
  hc_chart(backgroundColor = "white",zoomType = 'x') %>%
  hc_add_series_times_values(pricedata$variable, pricedata$value, name = "Price") %>%
  hc_annotations(list(xValue = currmonth, title = list(text = 'Annotated chart!')))

Here is the chart,

You can see the annotation is in the top left corner as [object][object].

EDIT :Tried the answer and it didn't work.

Answer 1

Following the example https://www.highcharts.com/demo/annotations, and reading this greate tutorial https://dantonnoriega.github.io/ultinomics.org/post/2017-04-05-highcharter-explainer.html it's possible.

First of all, it's better to create the chart using the hchart function.

library(tidyverse) # for pull and last
library(highcharter)

currmonth <- max(data$variable)
lastvalue <- data %>% pull(value) %>% last()

hc <- hchart(data, "line", hcaes(variable, value)) 

Then add the annotation replicating the given links:

hc %>% 
  hc_annotations(
      list(
          labelOptions = list(y = 50, x = 0),
          labels = list(
            list(
              point = list(
                x = highcharter::datetime_to_timestamp(currmonth),
                y = lastvalue,
                xAxis = 0,
                yAxis = 0
              ),
              text = scales::dollar(lastvalue)
              )
            )
          )
      )

Sadly highchartsJS need a lot of nested lists so that is what we need to do to add annotations in highcharter (by now)