Scales that Focus Specific Levels in your ggplot().
ggfocus
Introduction
In data analysis, one may want to visualize data for a specific subgroup of observations. Simply filtering out observations that do not belong to the subgroup may take the information out of context. Therefore, it is necessary to have tools that allow the analyst to draw attention (focus) on that subgroup within the complete relevant information available.
While ggplot2
is a great tool for data visualization in general, constructing graphics that focus on those subgroups may need very troublesome manipulation of data and graphical scales (for example colors) together, i.e. setting low alpha for unimportant observations, coloring things in a way that highlights the focused subgroup, etc.
ggfocus
allows you to build graphics that focus on those specific subgroups by doing the scale manipulation automatically while keeping all the flexibility from ggplot.
The idea behind this package is from this issue from tidyverse/ggplot2
.
Installing ggfocus
The package is available on CRAN, but you can also install the latest version from Github with devtools.
devtools::install_github("Freguglia/ggfocus") # Latest version
install.packages("ggfocus") # CRAN version
Usage
The workflow of ggfocus
is the same as any ggplot
graphic with the addition of the focus scales family of functions:
scale_color_focus(focus_levels = character(0), color_focus = NULL, color_other = "black", palette_focus = "Set1")
scale_fill_focus(focus_levels = character(0), color_focus = NULL, color_other = "gray", palette_focus = "Set1")
scale_alpha_focus(focus_levels = character(0), alpha_focus = 1, alpha_other = .05)
scale_linetype_focus(focus_levels = character(0), linetype_focus = 1, linetype_other = 3)
scale_shape_focus(focus_levels = character(0), shape_focus = 8, shape_other = 1)
scale_size_focus(focus_levels = character(0), size_focus = 3, size_other = 1)
The user should map the variable with the grouping variable to all the aes
used to highlight observations and then use these functions to automatically create scales that highlight a specified group of observations.
Both the selected and unselected groups characteristics are customizable with the parameters of focus scales. See the examples below.
Examples
Creating an example dataset.
library(ggfocus)
set.seed(1)
# Create an example dataset
df <- data.frame(u1 = runif(300),
u2 = runif(300),
grp = sample(LETTERS[1:10], 300, replace = TRUE))
dplyr::glimpse(df)
#> Observations: 300
#> Variables: 3
#> $ u1 <dbl> 0.26550866, 0.37212390, 0.57285336, 0.90820779, 0.20168193, 0.898…
#> $ u2 <dbl> 0.67371223, 0.09485786, 0.49259612, 0.46155184, 0.37521653, 0.991…
#> $ grp <fct> C, E, B, E, E, C, J, B, G, H, B, J, G, A, I, H, F, F, C, J, A, F,…
Visualizing with focus on observations such that grp
is A
or B
.
ggplot(df, aes(x = u1, y = u2, color = grp, alpha = grp)) +
geom_point() +
scale_color_focus(c("A", "B"), color_focus = c("blue", "red")) +
scale_alpha_focus(c("A", "B"))
Interaction with other extensions
Since ggfocus
creates the focused visualization solely by controlling scales, other ggplot
extensions and types of graphics can interact with it the same way, an example with the maps
package is shown below.
library(maps)
wm <- map_data("world")
ggplot(wm, aes(x=long, y = lat, group = group, fill = region)) +
geom_polygon(color="black") +
theme_void() +
scale_fill_focus(c("Brazil", "Canada", "Australia", "India"), color_other = "gray")