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Lære Inline Functions with apply | Anonymous Functions in R
Functions and Functional Programming in R

bookInline Functions with apply

The apply family of functions in R—apply, lapply, and sapply—are essential tools in functional programming, letting you perform operations on data structures efficiently without writing explicit loops. These functions allow you to apply a function to each element, row, or column of data, which is especially useful for data processing and analysis tasks.

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# Using lapply with an anonymous function to calculate the length of each word in a list words <- list("apple", "banana", "cherry") word_lengths <- lapply(words, function(word) nchar(word)) print(word_lengths)
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In this example, an anonymous function is defined directly inside the lapply call using the syntax function(word) nchar(word). This function takes each element of the words list, calculates its length using nchar, and returns the result. By defining the function inline, you avoid cluttering your code with extra function names and keep the logic close to where it's used.

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# Using sapply with an anonymous function to check if numbers in a vector are even numbers <- c(1, 2, 3, 4, 5) is_even <- sapply(numbers, function(x) x %% 2 == 0) print(is_even)
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While both lapply and sapply apply a function to each element of a list or vector, they differ in their output. lapply always returns a list, regardless of the result, making it more consistent when you need to preserve structure. sapply tries to simplify the result: if possible, it returns a vector or matrix instead of a list, making it convenient for operations that naturally result in simple data types. Use lapply when you want guaranteed list output, and sapply when you prefer a simplified result.

Note
Note

The apply family in R—apply, lapply, and sapply—are functions that help you apply operations to data structures like lists, vectors, and matrices. They are commonly used for data transformation, aggregation, and analysis tasks, making code more concise and readable compared to traditional loops.

1. What is the main benefit of using anonymous functions with apply?

2. How does lapply differ from sapply in terms of output?

3. Why might you use an anonymous function instead of a named function with apply?

question mark

What is the main benefit of using anonymous functions with apply?

Select the correct answer

question mark

How does lapply differ from sapply in terms of output?

Select the correct answer

question mark

Why might you use an anonymous function instead of a named function with apply?

Select the correct answer

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Sektion 2. Kapitel 3

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Suggested prompts:

Can you explain the difference between apply, lapply, and sapply in more detail?

When should I use lapply versus sapply in practice?

Can you give more examples of using anonymous functions with these apply functions?

bookInline Functions with apply

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The apply family of functions in R—apply, lapply, and sapply—are essential tools in functional programming, letting you perform operations on data structures efficiently without writing explicit loops. These functions allow you to apply a function to each element, row, or column of data, which is especially useful for data processing and analysis tasks.

1234
# Using lapply with an anonymous function to calculate the length of each word in a list words <- list("apple", "banana", "cherry") word_lengths <- lapply(words, function(word) nchar(word)) print(word_lengths)
copy

In this example, an anonymous function is defined directly inside the lapply call using the syntax function(word) nchar(word). This function takes each element of the words list, calculates its length using nchar, and returns the result. By defining the function inline, you avoid cluttering your code with extra function names and keep the logic close to where it's used.

1234
# Using sapply with an anonymous function to check if numbers in a vector are even numbers <- c(1, 2, 3, 4, 5) is_even <- sapply(numbers, function(x) x %% 2 == 0) print(is_even)
copy

While both lapply and sapply apply a function to each element of a list or vector, they differ in their output. lapply always returns a list, regardless of the result, making it more consistent when you need to preserve structure. sapply tries to simplify the result: if possible, it returns a vector or matrix instead of a list, making it convenient for operations that naturally result in simple data types. Use lapply when you want guaranteed list output, and sapply when you prefer a simplified result.

Note
Note

The apply family in R—apply, lapply, and sapply—are functions that help you apply operations to data structures like lists, vectors, and matrices. They are commonly used for data transformation, aggregation, and analysis tasks, making code more concise and readable compared to traditional loops.

1. What is the main benefit of using anonymous functions with apply?

2. How does lapply differ from sapply in terms of output?

3. Why might you use an anonymous function instead of a named function with apply?

question mark

What is the main benefit of using anonymous functions with apply?

Select the correct answer

question mark

How does lapply differ from sapply in terms of output?

Select the correct answer

question mark

Why might you use an anonymous function instead of a named function with apply?

Select the correct answer

Var alt klart?

Hvordan kan vi forbedre det?

Tak for dine kommentarer!

Sektion 2. Kapitel 3
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