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#Week 3 Lab Practice Questions
#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:") ; list_data
## [1] "List:"
## [[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:"
str (list_data)
## List of 2
##  $ : chr [1:3] "Red" "Green" "Black"
##  $ :List of 3
##   ..$ : chr "Python"
##   ..$ : chr "PHP"
##   ..$ : chr "Java"
length (list_data)
## [1] 2
length (list_data [[1]])
## [1] 3
length (list_data [[2]])
## [1] 3
#Write a R program to assign NULL to a given list element?
l = list (1, 2, 3, 4, 5)
#print ("Original list:")
print ("Original list:") ;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")
l [[2]] <- NULL
l [[2]] <- NULL 
print("Set 2nd and 3rd elements to NULL") ;l
## [1] "Set 2nd and 3rd elements to NULL"
## [[1]]
## [1] 1
## 
## [[2]]
## [1] 4
## 
## [[3]]
## [1] 5
str (l)
## List of 3
##  $ : num 1
##  $ : num 4
##  $ : num 5
#Write a R program to Add 10 to each element of the first  vector in a given list?
g1 = 1:10
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:")
list1 [["g1"]] <- g1 + 10
print ("New list:") ; 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:")
## [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 [["g1"]][-3]
## [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:")
## [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:")
list1 [["g4"]] <- "Python"
print ("Add a new vector to the said list:") ; 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:")
## [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"
length (list1 [["g1"]]);length (list1 [["g2"]])
## [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:")
## [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"

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