Filter legend in ggvis

Question

In this ggvis example, is there a way to filter the legend to reflect the input selection, e.g. only show "x" and "y" when "z" is not selected? This would be especially useful when the choices are extensive.

library(tidyverse)
library(ggvis)

data_df <- tibble(
  name = factor(c("x", "x", "x", "y", "y", "y", "z", "z", "z")), 
  quant = c(7, 8, 7, 8, 8, 8, 9, 9, 9), 
  year = factor(c(2014, 2015, 2016, 2014, 2015, 2016, 2014, 2015, 2016))
  )

data_df %>%
  ggvis(~ year, ~ quant, stroke = ~ name) %>%
  filter(name %in% eval(
    input_select(
      choices = levels(data_df$name),
      selected = c("x", "y"),
      selectize = TRUE,
      multiple = TRUE
    )
  )) %>%
  layer_lines()

Answer 1

I think this is what you would like?

library(tidyverse)
library(ggvis)

data_df <- tibble(
  name = c("x", "x", "x", "y", "y", "y", "z", "z", "z"), 
  quant = c(7, 8, 7, 8, 8, 8, 9, 9, 9), 
  year = factor(c(2014, 2015, 2016, 2014, 2015, 2016, 2014, 2015, 2016))
)

data_df %>%
  ggvis(~ year, ~ quant, stroke = ~ name) %>%
  filter(name %in% eval(
    input_select(
      choices = levels(as.factor(data_df$name)),
      selected = c("x", "y"),
      selectize = TRUE,
      multiple = TRUE
    )
  )) %>%
  layer_lines()