Practice 1: Write a R program to count number of objects in a given list?

list_data <- list(c("Red", "Green", "Black"), list("Python", "PHP", "Java"))
print("List:")

## [1] "List:"

print(list_data)

## [[1]]
## [1] "Red"   "Green" "Black"
## 
## [[2]]
## [[2]][[1]]
## [1] "Python"
## 
## [[2]][[2]]
## [1] "PHP"
## 
## [[2]][[3]]
## [1] "Java"

print("Number of objects in the said list:")

## [1] "Number of objects in the said list:"

print(lengths(list_data))

## [1] 3 3

Practice 2: Write a R program to assign NULL to a given list element?

l <- list(1, 2, 3, 4, 5)
print("Original list:")

## [1] "Original list:"

print(l)

## [[1]]
## [1] 1
## 
## [[2]]
## [1] 2
## 
## [[3]]
## [1] 3
## 
## [[4]]
## [1] 4
## 
## [[5]]
## [1] 5

print("Set 2nd and 3rd elements to NULL")

## [1] "Set 2nd and 3rd elements to NULL"

l[c(2, 3)] <- NULL
print(l)

## [[1]]
## [1] 1
## 
## [[2]]
## [1] 4
## 
## [[3]]
## [1] 5

Practice 3: Write a R program to Add 10 to each element of the first vector in a given list? Sample list: (g1 = 1:10, g2 = ”R Programming”, g3 = ”HTML”).

list1 <- list(g1 = 1:10, g2 = "R Programming", g3 = "HTML")
print("Original list:")

## [1] "Original list:"

print(list1)

## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"

print("New list:")

## [1] "New list:"

list1$g1 = list1$g1 + 10
print(list1)

## $g1
##  [1] 11 12 13 14 15 16 17 18 19 20
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"

Practice 4: Write a R program to extract all elements of a first vector except the third element of it from a given list. Sample list: (g1 = 1:10, g2 = ”R Programming”, g3 = ”HTML”).

list1 <- list(g1 = 1:10, g2 = "R Programming", g3 = "HTML")
print("Original list:")

## [1] "Original list:"

print(list1)

## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"

print("First vector:")

## [1] "First vector:"

print(list1$g1[-3])

## [1]  1  2  4  5  6  7  8  9 10

Practice 5: Write a R program to add a new item g4 = ”Python” to a given list. Sample list: (g1 = 1:10, g2 = ”R Programming”, g3 = ”HTML”).

list1 <- list(g1 = 1:10, g2 = "R Programming", g3 = "HTML")
print("Original list:")

## [1] "Original list:"

print(list1)

## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"

print("Add a new vector to the said list:")

## [1] "Add a new vector to the said list:"

list1$g4 = "Python"
print(list1)

## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"
## 
## $g4
## [1] "Python"

Practice 6: Write a R program to get the length of the first two vectors of a given list. Sample list: (g1 = 1:10, g2 = ”R Programming”, g3 = ”HTML”).

list1 <- list(g1 = 1:10, g2 = "R Programming", g3 = "HTML")
print("Original list:")

## [1] "Original list:"

print(list1)

## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"

print("Length of the vector g1 and g2 of the said list:")

## [1] "Length of the vector g1 and g2 of the said list:"

print(lengths(list1[c(1,2)]))

## g1 g2 
## 10  1

Practice 7: Write a R program to find all elements of a given list that are not in another given list? Hint, see setdiff(..).

l1 = list("x", "y", "z")
l2 = list("X", "Y", "Z", "x", "y", "z")
print("Original lists:")

## [1] "Original lists:"

print(l1)

## [[1]]
## [1] "x"
## 
## [[2]]
## [1] "y"
## 
## [[3]]
## [1] "z"

print(l2)

## [[1]]
## [1] "X"
## 
## [[2]]
## [1] "Y"
## 
## [[3]]
## [1] "Z"
## 
## [[4]]
## [1] "x"
## 
## [[5]]
## [1] "y"
## 
## [[6]]
## [1] "z"

print("All elements of l2 that are not in l1:")

## [1] "All elements of l2 that are not in l1:"

print(setdiff(l2, l1))

## [[1]]
## [1] "X"
## 
## [[2]]
## [1] "Y"
## 
## [[3]]
## [1] "Z"

End of Practice