List in R

The list in R contains several unique data types inside it. A collection of data that is ordered and editable is called a list in R.

We used the list() function to create a list:

# List of strings
l <- list("Python", "R", "Java")

# Print the list
l

Output

List in R

Access List in R

To access the list items, refer to its index number inside brackets. The first item has index 1, the second item has index 2, and so on:

l <- list("Python", "R", "Java")

l[1]

Output

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Change Item Value

Refer to the index number to change the value of a specific item:

l <- list("Python", "R", "Java")
l[1] <- "C++"

# Print the updated list
l

Output

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List Length

We can use the length() function to find out how many items a list has:

l <- list("Python", "R", "Java")

length(l)

Output

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Check if Item Exists

We can use the %in% operator to find out if a specified item is present in a list:

# Check if "Python" is present in the list:
l <- list("Python", "R", "Java")

"Python" %in% l

Output

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Add List Items

We can use the append() function to add an item to the end of the list:

# Add C++ in the list
l <- list("Python", "R", "Java")

append(l, "C++")

Output

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We can add “after=index number” in the append() function to add an item to the right of a specified index:

l <- list("Python", "R", "Java")

append(l, "C++", after = 2)

Output

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Remove List Items

List items can be removed from the list. Mentioned below example created a newly updated list without the “Python” item:

l <- list("Python", "R", "Java")

nl <- l[-1]

# Print the new list
nl

Output

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Indexes range

The range of indexes can be specified where to begin and where to close the range, by using the operator ( : ).

l <- list("Python", "R", "Java", "C++", "Ruby", "HTML")

(l)[2:4]

Output

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Loop Through a List

To loop through the list items we can use a for loop:

l <- list("Python", "R", "Java")

for (x in l) {
  print(x)
}

Output

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Join Two Lists

In R programming, there are many ways to concatenate two or more lists. To combine two elements together the c() function is used commonly:

l1 <- list("Python", "R", "Java")
l2 <- list(1,2,3)
l3 <- c(l1,l2)

l3

Output

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Merging Lists

One or more lists can be merged into one list in R programming. The list() function helps in merging. To merge the list you have to pass all lists in function as a parameter, then it returns a list that contains all the elements which are present in the lists. Check the mentioned merging process is done.

el <- list(2,4,6,8,10)  
ol <- list(1,3,5,7,9)  
    
merged.list <- list(el,ol)  
   
print(merged.list)

Output:

list12