Question 1:

Create the following vectors a, b, and c a) 2,5,6,7 b) 1,0,9,8 c) 6,5,8,3

Rowbind the vectors to form a 3X4 matrix. Change the column names to (Mon, Tue, Wed, Thu). Change the row names to (Present, Absent, On leave). Calculate the rowsums and the columnsums.

Answer 1:

First Let’s create the 3 vectors.

a<-c(2,5,6,7)
b<-c(1,0,9,8)
c<-c(6,5,8,3)

Then we combine the vectors into a matrix and print it.

mat<-matrix(c(a,b,c),byrow = TRUE,nrow = 3)
print(mat)
##      [,1] [,2] [,3] [,4]
## [1,]    2    5    6    7
## [2,]    1    0    9    8
## [3,]    6    5    8    3

Now we change the names and print.

colnames(mat)<-c('Mon', 'Tue', 'Wed', 'Thu')
rownames(mat)<-c('Present', 'Absent', 'On leave')
print(mat)
##          Mon Tue Wed Thu
## Present    2   5   6   7
## Absent     1   0   9   8
## On leave   6   5   8   3

Finally, we calculate the sums and print.

rsums<-rowSums(mat)
csums<-colSums(mat)
print(rsums)
##  Present   Absent On leave 
##       20       18       22
print(csums)
## Mon Tue Wed Thu 
##   9  10  23  18

We can also bind the sums with the matrix

mat<-cbind(mat,rsums)
total<-colSums(mat)
mat<-rbind(mat,total)
print(mat)
##          Mon Tue Wed Thu rsums
## Present    2   5   6   7    20
## Absent     1   0   9   8    18
## On leave   6   5   8   3    22
## total      9  10  23  18    60

Question 2:

Read in the dataset mtcars into a dataframe. Plot the following:

  1. Scatterplot of mpg vs disp
  2. Boxplot of mpg with gear
  3. Histogram of disp

Answer 2:

First, we read the dataset into a dataframe.

cars<-data.frame(mtcars)

Next we plot the charts

  1. Scatterplot of mpg vs disp
plot(cars$mpg,cars$disp,
     xlab = 'MPG',
     ylab = 'Disp',
     main = 'MPG vs Disp Plot',
     col = 'blue')

  1. Boxplot of mpg with gear
boxplot(cars$mpg~cars$gear,
     xlab = 'Gear',
     ylab = 'Distribution of MPG',
     main = 'Boxplot of MPG with Gear',
     col = 'light blue')

  1. Histogram of disp
hist(cars$disp,
     xlab = 'Disp',
     ylab = 'No of Observations',
     main = 'Histogram of Disp',
     col = 'green')

End of Assignment 2