Easily add significance bars to your ggplots
This package provides an easy way to indicate if two groups are significantly different. Commonly this is shown with a by a bar on top connecting the groups of interest which itself is annoted with the level of significance (NS, *, **, ***). The package provides a single layer (geom_signif) that takes the groups for comparison and the test (t.test, wilcox etc.) and adds the annotation to the plot.
Install package
install.packages("ggsignif")
# Or for the latest development version
devtools::install_github("const-ae/ggsignif")Plot significance
library(ggplot2)
library(ggsignif)
ggplot(mpg, aes(class, hwy)) +
geom_boxplot() +
geom_signif(comparisons = list(c("compact", "midsize"), c("minivan", "suv")),
map_signif_level = TRUE, textsize=5) +
ylim(NA, 50)Advanced Example
# Calculate annotation
anno <- t.test(iris[iris$Petal.Width > 1 & iris$Species == "versicolor", "Sepal.Width"],
iris[iris$Species == "virginica", "Sepal.Width"])$p.value
# Make plot with custom x and y position of the bracket
ggplot(iris, aes(x=Species, y=Sepal.Width, fill=Petal.Width > 1)) +
geom_boxplot(position="dodge") +
geom_signif(annotation=formatC(anno, digits=1),
y_position=4.05, xmin=2.2, xmax=3,
tip_length = c(0.2, 0.04))For further details go the CRAN page and check the examples in the vignette.