Lists


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: "); print(list_data)
## [1] "List: "
## [[1]]
## [1] "Red"   "Green" "Black"
## 
## [[2]]
## [[2]][[1]]
## [1] "Python"
## 
## [[2]][[2]]
## [1] "PHP"
## 
## [[2]][[3]]
## [1] "Java"
cat("Number of objects in the said list:", length(list_data))
## Number of objects in the said list: 2


Write a R program to assign NULL to a given list element?

l = list(1,2,3,4,5)
print("Original list:"); print(l)
## [1] "Original list:"
## [[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[2:3] <- NULL
print(l)
## [[1]]
## [1] 1
## 
## [[2]]
## [1] 4
## 
## [[3]]
## [1] 5


Write a R program to add 10 to each element of the first vector in a given list?

list1 <- list(g1 = 1:10, g2 = "R Programming", g3 = "HTML")
print("Original list:"); print(list1)
## [1] "Original list:"
## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"
list1$g1 <- list1$g1 + 10
print("New list:"); print(list1)
## [1] "New list:"
## $g1
##  [1] 11 12 13 14 15 16 17 18 19 20
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"


Write a R program to extract all elements of a first vector except the third element of it from a given list.

list1 <- list(g1 = 1:10, g2 = "R Programming", g3 = "HTML")
print("Original list:"); print(list1)
## [1] "Original list:"
## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"
print("First vector:"); print(list1$g1)
## [1] "First vector:"
##  [1]  1  2  3  4  5  6  7  8  9 10
print("First vector without the 3rd element:"); print(list1$g1[-3])
## [1] "First vector without the 3rd element:"
## [1]  1  2  4  5  6  7  8  9 10


Write a R program to add a new item g4 = ”Python” to a given list.

list1 <- list(g1 = 1:10, g2 = "R Programming", g3 = "HTML")
print("Original list:"); print(list1)
## [1] "Original list:"
## $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:"); list1 <- c(list1, g4 = "Python"); print(list1)
## [1] "Add a new vector to the said list:"
## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"
## 
## $g4
## [1] "Python"


Write a R program to get the length of the first two vectors of a given list.

list1 <- list(g1 = 1:10, g2 = "R Programming", g3 = "HTML")
print("Original list:"); print(list1)
## [1] "Original list:"
## $g1
##  [1]  1  2  3  4  5  6  7  8  9 10
## 
## $g2
## [1] "R Programming"
## 
## $g3
## [1] "HTML"
print("Length of the vector g1 & g2 of the said list:"); print(length(list1$g1)) ; print(length(list1$g2))
## [1] "Length of the vector g1 & g2 of the said list:"
## [1] 10
## [1] 1


Write a R program to find all elements of a given list that are not in another given list?

l1 = list("x", "y", "z")
l2 = list("X", "Y", "Z", "x", "y", "z")
print("Original lists:"); print(l1); print(l2)
## [1] "Original lists:"
## [[1]]
## [1] "x"
## 
## [[2]]
## [1] "y"
## 
## [[3]]
## [1] "z"
## [[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:"); setdiff(l2, l1)
## [1] "All elements of l2 that are not in l1:"
## [[1]]
## [1] "X"
## 
## [[2]]
## [1] "Y"
## 
## [[3]]
## [1] "Z"
End of Practice