PROGRAM 6

Author

PRACHETAN MS

Write a R script to construct a box plot showcasing the distribution of a continous variable, grouped by a categorical variable, using ggplot2’s fill aesthetic.

Step 1: Load Required Library

#Load ggplot2 package for visualization 
library(ggplot2)

Loads the ggplot2 package. Required for creating box plots and other visualizations.

Step 2: Explore the In-Built Dataset

# Use the built-in 'iris' dataset
# 'Petal.Width' is a continous variable
# 'Species' is a categorical grouping variable

str(iris)  # View structure of the dataset
'data.frame':   150 obs. of  5 variables:
 $ Sepal.Length: num  5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ...
 $ Sepal.Width : num  3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
 $ Petal.Length: num  1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
 $ Petal.Width : num  0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
 $ Species     : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 1 1 1 1 ...
head(iris) # View sample data
  Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1          5.1         3.5          1.4         0.2  setosa
2          4.9         3.0          1.4         0.2  setosa
3          4.7         3.2          1.3         0.2  setosa
4          4.6         3.1          1.5         0.2  setosa
5          5.0         3.6          1.4         0.2  setosa
6          5.4         3.9          1.7         0.4  setosa

str(iris) → Displays structure and data types head(iris) → Shows first few rows Helps identify: Petal.Width → Continuous variable Species → Categorical variable (grouping)

Step 3: Construct Box Plot With Grouping

Step 3.1

# Initialize ggplot with data aesthetic mappings
 p <- ggplot(data = iris, aes(x = Species, y = 
                                Petal.Width, fill = Species))

x = Species → Groups data by species y = Petal.Width → Displays distribution of petal width fill = Species → Adds color based on category

# Add the box plot layer

p <- p + geom_boxplot()
p

geom_boxplot() → Creates box plot Shows: Median Quartiles Outliers

# Add the box plot layer

p <- p + geom_boxplot()+
theme_minimal()+
theme(legend.position = 'top')
labs(title="IRIS box plot", x='Species',y='Petal.Width')
<ggplot2::labels> List of 3
 $ x    : chr "Species"
 $ y    : chr "Petal.Width"
 $ title: chr "IRIS box plot"
p

theme_minimal() → Clean layout legend.position = ‘top’ → Moves legend to top labs() → Adds title and axis labels

Conclusion:

Used iris dataset for analysis Created box plot of Petal Width grouped by Species Applied fill aesthetic for better visualization Enhanced plot with theme and labels