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:"
length(list_data)
## [1] 2

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 "
list
## function (...)  .Primitive("list")
l[2] <- list(NULL)
l[3] <- list(NULL)
l
## [[1]]
## [1] 1
## 
## [[2]]
## NULL
## 
## [[3]]
## NULL
## 
## [[4]]
## [1] 4
## 
## [[5]]
## [1] 5

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
list1
## $g1
##  [1] 11 12 13 14 15 16 17 18 19 20
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"

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:"
list1_new = list1[['g1']]
list1_new[-3]
## [1]  1  2  4  5  6  7  8  9 10

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"
list1
## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"
## 
## $g4
## [1] "Python"

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(paste("Length of 1st vector: ", length(list1[[1]])) )
## [1] "Length of 1st vector:  10"
print(paste("Length of 2nd vector: ", length(list1[[2]])) )
## [1] "Length of 2nd vector:  1"

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:"
setdiff(l2, l1)
## [[1]]
## [1] "X"
## 
## [[2]]
## [1] "Y"
## 
## [[3]]
## [1] "Z"