Program 4

Author

Tejaswini Reddy U

4. Develop a script in R to produce a bar graph displaying the frequency distribution of categorical data in a given dataset, grouped by specific variable, using ggplot2.

#LOAD necessary library
library(ggplot2)

Step 1 : Load the dataset

We use the built-in mtcars dataset, which contains information about different car models.

data <- mtcars
head(data)

                   mpg cyl disp  hp drat    wt  qsec vs am gear carb
Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

Step 2 : Convert Numeric Data into Categorical data

data$cyl<-as.factor(data$cyl)
data$gear<- as.factor(data$gear)

Step 3: Create bar graph

ggplot(data, aes(x=cyl,fill=gear))+
  geom_bar(position = "dodge")+
  labs(title = "frequncy of cylinders grouped by gear type",
       x="no.of cylinders",
       y="count",
       fill="gears")+
  theme_minimal()