如何在r-plotly中向折线图的峰值动态添加注释？

Question

I am trying to reproduce the code shown in this page , specifically the one named "Mix data manipulation and visualization verbs."

I literally just copy-pasted the code and made a few minor changes to get it to run ( plot_ly now requires column names to be referenced with a "~", etc). However, my graph looks very different:

What I have

I looked into annotations in plot_ly but it seems like the point needs to be hard-coded in, instead of being able to use filter automatically like the author did. (Unless I am misunderstanding.) This is what I'm using:

p4 <- plot_ly(economics, x = economics$date, y = economics$uempmed)

p4 %>%
  add_trace(y = fitted(loess(economics$uempmed ~ as.numeric(economics$date)))) %>%
  add_lines(x = economics$date, y = economics$uempmed) %>%
  layout(title = "Median duration of unemployment (in weeks)",
         showlegend = FALSE) %>%
  dplyr::filter(economics$uempmed == max(economics$uempmed)) %>%
  layout(annotations = list(x = economics$date, y = economics$uempmed, text = "Peak", showarrow = T))

I expected it to look like it does on the website (below), but it seems like the annotation text is just being spammed across the whole line instead of just staying at the max:

What it should look like

Can someone tell me what I'm doing wrong?

Answer 1

Why not pre-calcaualte the peak first before putting it in the chain

peak <- dplyr::filter(economics, uempmed == max(uempmed))
p4 %>%
  add_trace(y = fitted(loess(economics$uempmed ~ as.numeric(economics$date)))) %>%
  add_lines(x = economics$date, y = economics$uempmed) %>%
  layout(title = "Median duration of unemployment (in weeks)",
         showlegend = FALSE) %>%
  layout(annotations = list(x = peak$date, y = peak$uempmed, text = "Peak", showarrow = T))