add_tooltip does not work with layer_lines

[arjan-hada]

The tooltip only shows one value everywhere in the line.

# Function for the tooltip
all_values <- function(x) {
  if(is.null(x)) return(NULL)
  paste0(names(x), ": ", format(x), collapse = "
")
}

by_age <- gss_cat %>%
  filter(!is.na(age)) %>%
  group_by(age, marital) %>%
  count() %>%
  mutate(prop = n / sum(n))

ggvis(by_age, ~age, ~prop, stroke = ~marital) %>% 
  layer_lines() %>% 
  add_tooltip(all_values, "hover")