Thread by @selcukorkmaz

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🎯 Demystifying the #Apply Functions Family in #R 🎯

Are you an #Rstats enthusiast? Let's dive into the powerful 'apply' family of functions to help you manipulate and analyze data efficiently! 👩‍💻👨‍💻

#DataScience #RStats

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Meet the Family! 🏡

There are six main functions in the 'apply' family:

1️⃣ apply()
2️⃣ lapply()
3️⃣ sapply()
4️⃣ vapply()
5️⃣ mapply()
6️⃣ tapply()

Each has its own use case and is designed to work with different data structures. Let's explore them! 🕵️‍♂️🔍

#RStats

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1️⃣ apply()

Use apply() for applying a function across the rows or columns of a matrix or array.

Syntax: apply(X, MARGIN, FUN, ...)

X: array or matrix
MARGIN: 1 for rows, 2 for columns
FUN: function to apply
... : additional arguments

#RStats #DataScience

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2️⃣ lapply()

Use lapply() for applying a function to each element of a list or vector and returning a list.

Syntax: lapply(X, FUN, ...)

X: list or vector
FUN: function to apply
... : additional arguments

#Rstats #DataScience

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3️⃣ sapply()

sapply() is a simplified version of lapply(), returning a vector or matrix instead of a list.

Syntax: sapply(X, FUN, ..., simplify = TRUE)

X: list or vector
FUN: function to apply
... : additional arguments
simplify: to return a vector/matrix

#RStats

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4️⃣ vapply()

vapply() is a safer and more rigid version of sapply(). It requires you to specify the output type and length, ensuring consistency.

Syntax: vapply(X, FUN, FUN.VALUE, ..., USE.NAMES = TRUE)

FUN.VALUE: output type
USE.NAMES: keep names or not

#RStats

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5️⃣ mapply()

mapply() is a multivariate version of sapply(). It applies a function to multiple input lists or vectors, element-wise.

Syntax: mapply(FUN, ..., MoreArgs = NULL, SIMPLIFY = TRUE, USE.NAMES = TRUE)

MoreArgs: additional args
USE.NAMES: keep names or not

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6️⃣ tapply()

tapply() is great for applying a function to subsets of a vector, as defined by factors.

Syntax: tapply(X, INDEX, FUN, ..., simplify = TRUE)

X: vector
INDEX: list of factors
FUN: function to apply
... : additional args
simplify: return vector/matrix

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🔁 When to Use Which Function?

1️⃣ apply(): use with matrices/arrays for row/column operations
2️⃣ lapply(): use with lists/vectors, get a list output
3️⃣ sapply(): use with lists/vectors, get a vector/matrix output

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4️⃣ vapply(): use with lists/vectors, enforce output type
5️⃣ mapply(): use with multiple lists/vectors
6️⃣ tapply(): use with vector subsets defined by factors