Accessing List Elements
R provides two ways through which we can access the elements of a list. First one is the indexing method performed in the same way as a vector. In the second one, we can access the elements of a list with the help of names. It will be possible only with the named list.; we cannot access the elements of a list using names if the list is normal.
Let see an example of both methods to understand how they are used in the list to access elements.
Example 1: Accessing elements using index
# Creating a list containing a vector, a matrix and a list. list_data <- list(c("Shubham","Arpita","Nishka"), matrix(c(40,80,60,70,90,80), nrow = 2), list("BCA","MCA","B.tech")) # Accessing the first element of the list. print(list_data[1]) # Accessing the third element. The third element is also a list, so all its elements will be printed. print(list_data[3])
Output:
[[1]] [1] "Shubham" "Arpita" "Nishka" [[1]] [[1]][[1]] [1] "BCA" [[1]][[2]] [1] "MCA" [[1]][[3]] [1] "B.tech"
Example 2: Accessing elements using names
# Creating a list containing a vector, a matrix and a list. list_data <- list(c("Shubham","Arpita","Nishka"), matrix(c(40,80,60,70,90,80), nrow = 2),list("BCA","MCA","B.tech")) # Giving names to the elements in the list. names(list_data) <- c("Student", "Marks", "Course") # Accessing the first element of the list. print(list_data["Student"]) print(list_data$Marks) print(list_data)
Output:
$Student [1] "Shubham" "Arpita" "Nishka" [,1] [,2] [,3] [1,] 40 60 90 [2,] 80 70 80 $Student [1] "Shubham" "Arpita" "Nishka" $Marks [,1] [,2] [,3] [1,] 40 60 90 [2,] 80 70 80 $Course $Course[[1]] [1] "BCA" $Course[[2]] [1] "MCA" $Course[[3]] [1] "B. tech."