1 Using ggiraph

Any ‘ggplot’ graphic can be turned into a ‘ggiraph’ graphic by calling girafe() function.

1.1 Introduction

It extends ggplot2 with:

interactive geom functions: geom_point_interactive(), geom_col_interactive, etc.
interactive scale functions: scale_color_continuous_interactive(), scale_fill_manual_interactive(), etc.
interactive facet functions: facet_wrap_interactive() and facet_grid_interactive() that both work with labeller_interactive().
interactive guide functions: guide_colorbar_interactive(), guide_colourbar_interactive(), guide_legend_interactive().
interactive theme elements: element_line_interactive(), element_rect_interactive(), element_text_interactive(), label_interactive.

These understand three main aesthetics to let you add interactivity:

tooltip: column of dataset that contains tooltips to be displayed when mouse is over elements.
data_id: column of dataset that contains id to be associated with elements. This aesthetic is mandatory when you want to use an hover effect or when you want to enable selection of points in shiny applications.
onclick: column of dataset that contains javascript function to be executed when elements are clicked.

The following example use column ‘carname’ as tooltip value and as identifier for animations. The following ‘ggiraph’ features are used: - Elements associated with a tooltip are animated upon mouse over with the corresponding tooltip. - Elements associated with a data_id are animated upon mouse over. Note that data_id can also be reused within a shiny application as a reactive value. - Option hover_nearest=TRUE makes the hover effect applied on the nearest element while moving the mouse (in this case it is mandatory to also set the data_id parameter).

library(ggiraph)
library(tidyverse)

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

gg <- ggplot(
  data = mtcars_db,
  mapping = aes(
    x = disp, y = qsec,
    # here we add iteractive aesthetics
    tooltip = carname, data_id = carname
  )) + geom_point_interactive(
    size = 3, hover_nearest = TRUE)

# turn as girafe
girafe(ggobj = gg)

The same principle applies to all usual ggplot geometries. Let’s illustrate now with an interactive bar chart. The bars are animated according to their values in column ‘cut’.

p1 <- ggplot(
  data = diamonds, 
  mapping = aes(x = color, fill = cut, data_id = cut)) +
  geom_bar_interactive(
    aes(tooltip = sprintf("%s: %.0f", fill, after_stat(count)))
  )

girafe(ggobj = p1)

1.2 Interactive scales

Scales can also be made interactive with many ‘scale’ functions, for example scale_fill_manual_interactive():

p1 <- p1 + scale_fill_manual_interactive(
    values = c(
      Fair = "#0072B2", Good = "#009E73", 
      "Very Good" = "yellow", "Premium" = "orange", 
      "Ideal" = "red"),
    data_id = function(x) x, tooltip =  function(x) x)

girafe(ggobj = p1)

1.3 Interactive faceting

By using facet_wrap_interactive() and labeller_interactive, it is possible to make the strips interactive.

The following code add interactivity on text of strips instead of background of strips because we use the transparent theme.

p1 <- p1 + facet_wrap_interactive(
    ncol = 2, interactive_on = "text",
    vars(clarity),
    labeller = labeller_interactive(aes(
      tooltip = paste("this is clarity", clarity), data_id = clarity
    ))
  )

girafe(ggobj = p1)

This feature is handy in shiny applications where users can click on a strip to operate calculations only on the corresponding subset.

1.4 Click actions with JavaScript

Click actions must be a string column in the dataset containing valid javascript instructions. The onclick argument can be used to specify a JavaScript function that should be executed when a point, bar or any graphical element is clicked.

Here is an example of how you might use the onclick argument in the ggiraph package:

library(flextable)
library(ggiraph)
crimes <- readRDS(file = "data/crimes.RDS")
crimes

Murder	Assault	UrbanPop	Rape	state
numeric	integer	integer	numeric	character
13.2	236	58	21.2	alabama...
10.0	263	48	44.5	alaska...
8.1	294	80	31.0	arizona...
8.8	190	50	19.5	arkansas...
9.0	276	91	40.6	california...
7.9	204	78	38.7	colorado...
3.3	110	77	11.1	connecticut...
5.9	238	72	15.8	delaware...
15.4	335	80	31.9	florida...
17.4	211	60	25.8	georgia...
n: 50

library(htmltools)

gg_crime <- ggplot(crimes, aes(x = Murder, y = Assault)) +
  geom_point_interactive(
    hover_nearest = TRUE,
    aes(tooltip = state, 
        onclick = sprintf("window.open(\"http://en.wikipedia.org/wiki/%s\")", state), 
        data_id = state),
    size = 3
  )

girafe(ggobj = gg_crime)

1.5 Events within shiny

When working with shiny, you can use the data_id aesthetic to associate points, polygons and other graphical elements with a value that will be available in a reactive context. This makes it possible to click on an element and trigger an action. ‘ggiraph’ provides a reactive value with click and with hovering actions.

data_id aesthetic is a great and easy way to trigger actions when an element such as a point or a region on a map is clicked. The selected data_id for elements in panels, scales and themes are stored in 3 different reactive values. [Read more about shiny integration] in #shiny.

1.6 Arrange multiple plots into a grid

There are two avalaible options to arrange ggiraph outputs into a grid. As ‘ggiraph’ is a ‘ggplot’ extensions, package cowplot and patchwork can be used seamlessly to arrange plots in a grid before calling girafe().

library(patchwork)

mtcars_db <- mtcars |>
  rownames_to_column(var = "carname")

gg1 <- ggplot(mtcars_db) +
  geom_point_interactive(aes(x = drat, y = wt, color = qsec, 
    tooltip = carname, data_id = carname ), 
    hover_nearest = TRUE, size = 3) 

gg2 <- ggplot(mtcars_db) +
  geom_point_interactive(aes(x = qsec, y = disp, color = mpg, 
    tooltip = carname, data_id = carname ),
    hover_nearest = TRUE, size = 3)

Mouseover points to see where they are located in the other graph.

girafe( code = print(gg1 + gg2))