8  Configuring selections

The graphics produced by girafe() from a shiny application allows you to retrieve the element selections made by users.

Elements associated with data_id can be selected and the selection (the data_id value) is available in the client and the server side of the application. The selected identifiers will be the values mapped by the aesthetic data_id.

8.1 Type of selection

The selection type can take several values: single, multiple or none.

• single: the user can only select one element. The click allows its selection if it is not selected, or its de-selection if it is already selected. Clicking on an unselected element automatically de-selects the other selected element.
• multiple: the user can select several elements. He can do this by clicking on the elements or by selecting in the toolbar the “lasso selection” menu which allows you to draw a lasso on the graph and select all the elements contained in the lasso. The toolbar also contains an “anti-lasso selection” menu that allows you to draw a lasso on the graph and de-select all the elements contained in the lasso. The click is of course available for unit selections/de-selections.
• none: no selection is allowed in the graph produced by girafe.

All these options can be configured with the following functions:

• opts_selection(): relative to panel selections
• opts_selection_key(): relative to legend selections
• opts_selection_theme(): relative to theme elements selections

The following code is enabling single selection in the panel:

library(tidyverse)
mtcars_db <- rownames_to_column(mtcars, var = "carname")

gg_scatter <- ggplot(
  data = mtcars_db, 
  mapping = aes(
    x = disp, y = qsec, tooltip = carname, 
    data_id = carname, color= wt)) +
    geom_point_interactive(size=3)

girafe(ggobj = gg_scatter, 
  options = list(
    opts_selection(
      type = "single", 
      only_shiny = FALSE))
)

Note that we used only_shiny = FALSE so that selections can be seen in the page, in shiny applications, you don’t have to set this argument to FALSE.

8.2 Initial selection

Sometimes, it can be useful to pre-select some elements. This can be done by using the argument selected of function opts_selection (or opts_selection_key or opts_selection_theme).

preselection <- mtcars_db$carname[1:5]
girafe(ggobj = gg_scatter, 
  options = list(
    opts_selection(
      selected = preselection, 
      type = "multiple", 
      only_shiny = FALSE
    )
  )
)