 # Question: What Is Mapply?

## What is factor R?

Conceptually, factors are variables in R which take on a limited number of different values; such variables are often refered to as categorical variables.

Factors in R are stored as a vector of integer values with a corresponding set of character values to use when the factor is displayed.

….

## What is Lapply and Sapply in R?

lapply returns a list of the same length as X , each element of which is the result of applying FUN to the corresponding element of X . sapply is a user-friendly version and wrapper of lapply by default returning a vector, matrix or, if simplify = “array” , an array if appropriate, by applying simplify2array() .

## What package is Lapply in R?

laply is a function in Hadley’s “plyr” package.

## What is tapply?

tapply in R. Apply a function to each cell of a ragged array, that is to each (non-empty) group of values given by a unique combination of the levels of certain factors. Basically, tapply() applies a function or operation on subset of the vector broken down by a given factor variable.

## What does tapply return in R?

When FUN is present, tapply calls FUN for each cell that has any data in it. If FUN returns a single atomic value for each such cell (e.g., functions mean or var ) and when simplify is TRUE , tapply returns a multi-way array containing the values, and NA for the empty cells.

## What does Rep () do in R?

Let’s look at the function rep , which means “repeat”, and which can take a variety of different arguments. In the simplest case, it takes a value and the number of times to repeat that value. As with many functions in R—which is obsessed with vectors—the thing to be repeated can be a vector with multiple elements.

## How do you apply the same function to all rows and columns of a matrix?

The apply() function splits up the matrix in rows. Remember that if you select a single row or column, R will, by default, simplify that to a vector. The apply() function then uses these vectors one by one as an argument to the function you specified. So, the applied function needs to be able to deal with vectors.

## Is Lapply faster than for loop?

The apply functions (apply, sapply, lapply etc.) are marginally faster than a regular for loop, but still do their looping in R, rather than dropping down to the lower level of C code. … Essentially, this means calling a function that runs its loops in C rather than R code.

## How do I apply a function to every row in R?

To call a function for each row in an R data frame, we shall use R apply function. The second argument 1 represents rows, if it is 2 then the function would apply on columns. Following is an example R Script to demonstrate how to apply a function for each row in an R Data Frame.

## What is a vector in R?

A vector is the simplest type of data structure in R. Simply put, a vector is a sequence of data elements of the same basic type. Members of a vector are called Components. Here is a vector containing three numeric values 2, 3 and 5 : c(2, 3, 5)  2 3 5. And here is a vector of logical values.

## What is GL in R?

In mathematics, the general linear group of degree n is the set of n×n invertible matrices, together with the operation of ordinary matrix multiplication. … For example, the general linear group over R (the set of real numbers) is the group of n×n invertible matrices of real numbers, and is denoted by GLn(R) or GL(n, R).

## What is the difference between Lapply and Sapply?

If the programmers want the output to be a data frame or a vector, then sapply function is used whereas if a programmer wants the output to be a list then lapply is used. There is one more function known as vapply which is preferred over sapply, as vapply allows the programmer to specify the output type.

## Which function is very similar to Lapply?

Vector output: sapply and vapply sapply() and vapply() are very similar to lapply() except they simplify their output to produce an atomic vector. While sapply() guesses, vapply() takes an additional argument specifying the output type.

## What is the max function in R?

max returns the position of the element with the maximal value in a vector.