R boxplot() Function - Drawing Box Plots
R Language ExamplesThe R boxplot() function is used to draw box plots, showing the distribution characteristics and outliers of data.
The box plot displays the five-number summary of data (minimum, Q1, median, Q3, maximum) as well as outliers.
The syntax of the boxplot() function is as follows:
boxplot(x, horizontal = FALSE, col = NULL,
main = "", xlab = "", ylab = "")
Parameter Description:
xA numeric vector or formula (such as value ~ group).
Example
# Score data for multiple classes
class_a <- c(78, 82, 85, 88, 90, 75, 80, 86, 92, 84)
class_b <- c(72, 75, 78, 76, 80, 70, 74, 77, 79, 73)
class_c <- c(85, 88, 90, 92, 95, 80, 87, 89, 91, 86)
# Draw box plot
boxplot(class_a, class_b, class_c,
names = c(Class A, Class B, Class C),
main = Comparison of score distributions across classes,
xlab = Class,
ylab = Score,
col = c("skyblue", "lightgreen", "coral"))
class_a <- c(78, 82, 85, 88, 90, 75, 80, 86, 92, 84)
class_b <- c(72, 75, 78, 76, 80, 70, 74, 77, 79, 73)
class_c <- c(85, 88, 90, 92, 95, 80, 87, 89, 91, 86)
# Draw box plot
boxplot(class_a, class_b, class_c,
names = c(Class A, Class B, Class C),
main = Comparison of score distributions across classes,
xlab = Class,
ylab = Score,
col = c("skyblue", "lightgreen", "coral"))
Running the above code will display a box plot comparison of scores for the three classes.
Using the formula form of boxplot() is more convenient for grouped data:
Example
# Using formula form
scores <- c(class_a, class_b, class_c)
groups <- rep(c(Class A, Class B, Class C), each = 10)
boxplot(scores ~ groups,
main = Box plots of scores by class,
col = rainbow(3))
scores <- c(class_a, class_b, class_c)
groups <- rep(c(Class A, Class B, Class C), each = 10)
boxplot(scores ~ groups,
main = Box plots of scores by class,
col = rainbow(3))