Add Annotations to time series with highcharter

Question

I want to add annotations with Highcharter. I could do it with "classic" scatter plots :

library(highcharter)
df <- data.frame(
  x = 1:10,
  y = 1:10
)
hchart(df,"line", hcaes(x = x, y = y))  %>%
  hc_annotations(
    list(
      labels = lapply(1:nrow(df),function(i){
        list(point = list(x = df$x[i],y = df$y[i],xAxis = 0,yAxis = 0))
      })
    )
  )

The problem is I would like to do it when my X axis is a Date and somehow I can't make it work

df <- data.frame(
  x = seq(as.Date("2021-01-01"),as.Date("2021-01-10"),by = "days"),
  y = 1:10
)
hchart(df,"line", hcaes(x = x, y = y))  %>%
  hc_annotations(
    list(
      labels = lapply(1:nrow(df),function(i){
        list(point = list(x = df$x[i],y = df$y[i],xAxis = 0,yAxis = 0))
      })
    )
  )

Answer 1

Highcharter likes a timestamp when you use dates like this. Try using the datetime_to_timestamp function as below and include text in your list along with point.

library(highcharter)

df <- data.frame(
  x = seq(as.Date("2021-01-01"),as.Date("2021-01-10"),by = "days"),
  y = 1:10
)

hchart(df, "line", hcaes(x = x, y = y))  %>%
  hc_annotations(
    list(
      labels = lapply(1:nrow(df),function(i){
        list(
          point = list(
            x = datetime_to_timestamp(df$x[i]),
            y = df$y[i],
            xAxis = 0,
            yAxis = 0
            ),
          text = as.character(df$y[i])
          )
      })
    )
  )