Indexing List Elements
List elements can be accessed in several ways. And just like in vectors, indexing starts at 1.
Access by Index
Elements in a list can be accessed with either single or double brackets:
- Using single brackets (
[ ]) returns the element as a list; - Using double brackets (
[[ ]]) returns the value itself.
Example
123456test <- list(text = "Text", number = 42, logical = TRUE) # Extract as list test[2] # Extract as value test[[2]]
Access by Label
If a list has labels, you can extract elements using those labels. Just like with indices, you can use single brackets ([ ]) to return a list or double brackets ([[ ]]) to return the value. Additionally, the dollar sign ($) provides a shorthand for accessing values.
Example
1234567test <- list(text = "Text", number = 42, logical = TRUE) # Extract as list test["text"] # Extract as value test[["text"]] test$text
Swipe to start coding
You have a list info with course information.
You task is to:
- Extract the first element as a list.
- Output the class of this element with the
class()function. - Extract the fourth element as a numeric type.
- Output the class of this element with the
class()function.
Solution
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List elements can be accessed in several ways. And just like in vectors, indexing starts at 1.
Access by Index
Elements in a list can be accessed with either single or double brackets:
- Using single brackets (
[ ]) returns the element as a list; - Using double brackets (
[[ ]]) returns the value itself.
Example
123456test <- list(text = "Text", number = 42, logical = TRUE) # Extract as list test[2] # Extract as value test[[2]]
Access by Label
If a list has labels, you can extract elements using those labels. Just like with indices, you can use single brackets ([ ]) to return a list or double brackets ([[ ]]) to return the value. Additionally, the dollar sign ($) provides a shorthand for accessing values.
Example
1234567test <- list(text = "Text", number = 42, logical = TRUE) # Extract as list test["text"] # Extract as value test[["text"]] test$text
Swipe to start coding
You have a list info with course information.
You task is to:
- Extract the first element as a list.
- Output the class of this element with the
class()function. - Extract the fourth element as a numeric type.
- Output the class of this element with the
class()function.
Solution
Switch to desktop for real-world practiceContinue from where you are using one of the options belowThanks for your feedback!
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