如何在绘图中添加水平或垂直参考线的注释？

Question

I am using plotly for R. output using shiny if that matters. I want to add annotations to horizontal or vertical reference line created by layout(shapes = ) . It should be able to dynamically change position so that it stays visible no matter how plotly graph is zoomed in or out. Approximate Example

So far I can only find fixed location text. I don't mind if it is dynamically located on axis or arrow pointing to reference lines.

%Edited

I found the sulotion to the problem:

dt <- data.table(x = 1:10, y = rnorm(10))    
annotation <- list(yref = 'paper', xref = "x", y = 0, x = 2, text = "annotation")
plot_ly(type = "scatter", mode = "lines") %>% add_trace(x = dt$x, y = dt$y, mode = "lines") %>% layout(annotations= list(annotation))

Basically, yref = "paper" allow you to specify a position that is always relative to the plot, y=1 refers to the top of plot and y=0 refers to the bottom of the plot

Answer 1

I found the sulotion to the problem:

dt <- data.table(x = 1:10, y = rnorm(10))    
annotation <- list(yref = 'paper', xref = "x", y = 0, x = 2, text = "annotation")
plot_ly(type = "scatter", mode = "lines") %>% add_trace(x = dt$x, y = dt$y, mode = "lines") %>% layout(annotations= list(annotation))

Basically, yref = "paper" allow you to specify a position that is always relative to the plot, y=1 refers to the top of plot and y=0 refers to the bottom of the plot