Tooltip missing for geom_line_interactive in ggiraph

Question

I wanted to add tooltip to ggsurvplot. I am using ggiraph to display the plot. Since ggiraph does not have geom_step_interactive, I am manipulating my the data output of ggsurvplot to get the step function values and using geom_line_interactive to overlay a line on my ggsurvplot and add a tooltip. Here is the code that is working correctly:

library(ggiraph)
library(survminer)
library(survival)

  #Function to get the step function points
  step_func <- function(data, direction="hv", x , y) {
    direction <- match.arg(direction, c("hv", "vh"))
    data <- as.data.frame(data)[order(data[, x]), ]
    n <- nrow(data)

    if (n <= 1) {
      # Need at least one observation
      return(data[0, , drop = FALSE])
    }

    if (direction == "vh") {
      xs <- rep(1:n, each = 2)[-2*n]
      ys <- c(1, rep(2:n, each = 2))
    } else {
      ys <- rep(1:n, each = 2)[-2*n]
      xs <- c(1, rep(2:n, each = 2))
    }

    return(data.frame(
      x = data[,x][xs],
      y = data[,y][ys],
      data[xs, setdiff(names(data), c(x, y))]
    ))
  }



  fit<- survfit(Surv(time, status) ~ sex, data = lung )
  g <- ggsurvplot(fit, data = lung, risk.table = TRUE,
                  risk.table.pos= "out", risk.table.y.text = TRUE)

  dat1 <- plyr::ddply(g$plot$data, "strata", step_func, "hv", "time", "surv")
  dat1$tooltip <- paste0("Time:", dat1$x)
  gg<- g$plot+geom_line_interactive(data = dat1, aes(x= x, y=y, colour = strata, tooltip= tooltip ), size = .75)
  ggiraph(code = print(gg))

With the above code I get the following plot with tooltip as displayed in the image:

I want the tooltip not only show the time but also the survival probability, for that I change the code slightly as follows:

dat1$tooltip <- paste0("Time:", dat1$x, "Surv:", dat1$y )

This causes the tooltip to disappear.

What am I doing wrong?

Answer 1

It seems the geom_line_interactive tooltips vanish when they get too long. You can truncate the values result to keep them short. The following works:

dat1$tooltip <- paste0("Time:", dat1$x, " Surv:", round(dat1$y,2) )

but setting the value to 3 causes them to vanish. I am not completely sure of this because the tooltips are extremely fiddly and seemingly only appear when the the mouse is in exactly the right place. It could be that all of them over a certain length are suppressed.

I did notice however that the whole tooltip thing works much better if you use geom_point_interactive instead of geom_line_interactve and with larger size parameter values. That is probably what you want to do.

Could be that geom_line_interactive is ignoring the size parameter.

This figure is with geom_point_interactive, the round parameter above set to 3, and the size set to 1.75, and it works much better.