1. What is a list in R?
Answer:
Explanation:
A list in R is a collection that can hold elements of different types, including numbers, strings, vectors, and even other lists.
2. How do you create a list in R?
Answer:
Explanation:
The list() function is used to create a list in R.
3. How do you access the third element of a list named 'myList' in R?
Answer:
Explanation:
Double square brackets [[ ]] are used to access a single element of a list in R.
4. How can you add an element to an existing list in R?
Answer:
Explanation:
The append() function is used to add elements to an existing list in R.
5. What does the lapply() function do in R?
Answer:
Explanation:
The lapply() function applies a function to each element of a list and returns a list of the results.
6. How do you remove an element from a list in R?
Answer:
Explanation:
To remove an element from a list, you can set it to NULL using list$element <- NULL.
7. Which function checks if an object is a list in R?
Answer:
Explanation:
The is.list() function is used to check if an object is a list in R.
8. How do you concatenate two lists in R?
Answer:
Explanation:
The c() function can be used to concatenate two or more lists in R.
9. What is the result of the expression length(list(1, 2, 3, 4)) in R?
Answer:
Explanation:
The length() function returns the number of elements in a list, so length(list(1, 2, 3, 4)) is 4.
10. How do you create a named list in R?
Answer:
Explanation:
A named list is created by specifying the name of each element in the list() function, as in list(name = "value").
11. How do you access a named element 'age' in a list named 'person' in R?
Answer:
Explanation:
In R, a named element of a list can be accessed using either the $ operator (person$age) or the [ ] operator with the name as a string (person["age"]).
12. What does the sapply() function do in R?
Answer:
Explanation:
The sapply() function in R applies a function to each element of a list and simplifies the result into a vector or matrix.
13. How do you update an existing element in a list in R?
Answer:
Explanation:
To update an existing element in a list, you can use the $ operator or the [ ] operator, such as list$element <- new_value or list[element] <- new_value.
14. How do you check if a list is empty in R?
Answer:
Explanation:
To check if a list is empty in R, you can use the condition length(list) == 0.
15. What is the outcome of combining a list and a vector using the c() function in R?
Answer:
Explanation:
When a list and a vector are combined using the c() function, the result is a list containing the elements of both the original list and the vector.