Homework 1

#load mtcars dataset
df=read.csv("mtcars-3.csv")

Data Understanding

#Displaying the First Few Rows
head(mtcars-3)

#Dimension of Dataset
dim(mtcars-3)

## [1] 32 11

#Data Structure of Variable df
class(df)

## [1] "data.frame"

#Data Types of Columns
class(df$mpg)

## [1] "numeric"

typeof(df$mpg)

## [1] "double"

class(df$hp)

## [1] "integer"

typeof(df$hp)

## [1] "integer"

class(df$am)

## [1] "integer"

typeof(df$am)

## [1] "integer"

#Summary of Dataset
summary(df)

##     model                mpg             cyl             disp      
##  Length:32          Min.   :10.40   Min.   :4.000   Min.   : 71.1  
##  Class :character   1st Qu.:15.43   1st Qu.:4.000   1st Qu.:120.8  
##  Mode  :character   Median :19.20   Median :6.000   Median :196.3  
##                     Mean   :20.09   Mean   :6.188   Mean   :230.7  
##                     3rd Qu.:22.80   3rd Qu.:8.000   3rd Qu.:326.0  
##                     Max.   :33.90   Max.   :8.000   Max.   :472.0  
##        hp             drat             wt             qsec      
##  Min.   : 52.0   Min.   :2.760   Min.   :1.513   Min.   :14.50  
##  1st Qu.: 96.5   1st Qu.:3.080   1st Qu.:2.581   1st Qu.:16.89  
##  Median :123.0   Median :3.695   Median :3.325   Median :17.71  
##  Mean   :146.7   Mean   :3.597   Mean   :3.217   Mean   :17.85  
##  3rd Qu.:180.0   3rd Qu.:3.920   3rd Qu.:3.610   3rd Qu.:18.90  
##  Max.   :335.0   Max.   :4.930   Max.   :5.424   Max.   :22.90  
##        vs               am              gear            carb      
##  Min.   :0.0000   Min.   :0.0000   Min.   :3.000   Min.   :1.000  
##  1st Qu.:0.0000   1st Qu.:0.0000   1st Qu.:3.000   1st Qu.:2.000  
##  Median :0.0000   Median :0.0000   Median :4.000   Median :2.000  
##  Mean   :0.4375   Mean   :0.4062   Mean   :3.688   Mean   :2.812  
##  3rd Qu.:1.0000   3rd Qu.:1.0000   3rd Qu.:4.000   3rd Qu.:4.000  
##  Max.   :1.0000   Max.   :1.0000   Max.   :5.000   Max.   :8.000

#Change Class of Variable "am"
am=df$am
am=as.logical(am)

class(am)

## [1] "logical"

Scatter Plot

plot(df$hp, df$mpg,
main="Scatter Plot of MPG and HP",
xlab="hp",
ylab="mpg",
col="purple",
pch=20,
)

Interpretation of Scatter Plot
This graph shows that the lower the horsepower of car, the higher its mileage. The higher a car’s horsepower is, the worse its mileage is.

Bar Chart

library(ggplot2)
count_cyl=data.frame(table(df$cyl))
ggplot(data=count_cyl,aes(x=Var1, y=Freq)) + 
  geom_bar(stat="identity",fill="darkblue")+
  labs(title="Distribution of Cars According to Number of Cylinders", x="Num of Cylinders",y="Count of Cars")+
         scale_y_continuous(
           breaks=seq(0,20, by=1),
           labels=c("0","1","2","3","4","5","6","7","8","9","10","11","12","13","14","15","16","17","18","19","20"),
           limits=c(0,14),
           expand=c(0.02,0)
         )

Histogram

hist(x=df$mpg,
     xlab="MPG",
     ylab="Count of Cars",
     main="Distribution of Miles Per Gallon",
     col="lightgreen")