#Assigning the function data.frame to the object called mydata.

mydata <- data.frame("ID" = c(1, 2, 3, 4, 5, 6), 
                     "Age" = c(20, 25, 21, 18, 24, 23), 
                     "Gender" = c(1, 2, 2, 1, 1, 2)) 

print(mydata) #Showing the data set
##   ID Age Gender
## 1  1  20      1
## 2  2  25      2
## 3  3  21      2
## 4  4  18      1
## 5  5  24      1
## 6  6  23      2
mydata2 <- mydata[-4 , c(1, 2)] #Excluding the 4th row and selecting only the 1st and the 2nd column.
print(mydata2)
##   ID Age
## 1  1  20
## 2  2  25
## 3  3  21
## 5  5  24
## 6  6  23
mydata[1, 2] <- 22
print(mydata)
##   ID Age Gender
## 1  1  22      1
## 2  2  25      2
## 3  3  21      2
## 4  4  18      1
## 5  5  24      1
## 6  6  23      2
mydata$Height <- c(180, 172, 172, 178, 182, 169) #Adding a new variable Height to exisiting data frame, named mydata.

print(mydata)
##   ID Age Gender Height
## 1  1  22      1    180
## 2  2  25      2    172
## 3  3  21      2    172
## 4  4  18      1    178
## 5  5  24      1    182
## 6  6  23      2    169
#Creating new variable, named GenderF, which is factor (categorical variables) with categories 1 and 2 where 1 means Male and 2 Female.
mydata$GenderF <- factor(mydata$Gender,
                         levels = c(1, 2),
                         labels = c("M", "F"))
 
print(mydata)                        
##   ID Age Gender Height GenderF
## 1  1  22      1    180       M
## 2  2  25      2    172       F
## 3  3  21      2    172       F
## 4  4  18      1    178       M
## 5  5  24      1    182       M
## 6  6  23      2    169       F