# sweep function in R

sweep function in R applies an operation to a data matrix by row or column. The function takes five arguments: `x`, `MARGIN`, `STATS`, `FUN`, and any additional arguments.

The `sweep` function in R is a powerful tool for performing matrix operations, particularly for data manipulation and analysis.

It is a versatile function that can be used to apply various mathematical operations to a data matrix by row or column, making it an essential tool for data scientists and analysts.

The `sweep` function is particularly useful when working with large datasets, as it allows you to perform complex operations quickly and efficiently.

With its ability to apply different operations, such as addition, subtraction, multiplication, and division, the `sweep` function can be used to solve a wide range of problems in data analysis, including data transformation, aggregation, and filtering.

In this article, we will explore the basics of the `sweep` function in R, including its syntax, parameters, and examples.

We will also demonstrate how to use the `sweep` function to perform various matrix operations, such as adding a constant value to each row or column, and applying different mathematical operations to a data matrix.

## sweep function in R

Here are three examples of using the `sweep` function:

### Example 1: Simple `sweep` function in R

```data <- matrix(0, nrow = 6, ncol = 4)
data_ex1 <- sweep(x = data, MARGIN = 1, STATS = 5, FUN = "+")
print(data_ex1)```

This code adds the value 5 to each cell in the matrix.

`     [,1] [,2] [,3] [,4][1,]    5    5    5    5[2,]    5    5    5    5[3,]    5    5    5    5[4,]    5    5    5    5[5,]    5    5    5    5[6,]    5    5    5    5`

### Example 2: Complex STATS Specification

```data_ex2 <- sweep(x = data, MARGIN = 1, STATS = c(1, 3, 0, 2, 10, 5), FUN = "+")
print(data_ex2)```

This code adds different values to each row of the matrix.

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`      [,1] [,2] [,3] [,4][1,]    1    1    1    1[2,]    3    3    3    3[3,]    0    0    0    0[4,]    2    2    2    2[5,]   10   10   10   10[6,]    5    5    5    5`

### Example 3: Changing MARGIN Argument

```data_ex3 <- sweep(x = data, MARGIN = 2, STATS = c(1, 3, 0, 2), FUN = "+")
print(data_ex3)```
`      [,1] [,2] [,3] [,4][1,]    1    3    0    2[2,]    1    3    0    2[3,]    1    3    0    2[4,]    1    3    0    2[5,]    1    3    0    2[6,]    1    3    0    2`

This code adds values to each column of the matrix. However, since the length of `STATS` is shorter than the number of columns, the operation recycles across the end of each row.

To fix this, we can specify the length of `STATS` to match the number of columns:

```data_ex3_b <- sweep(x = data, MARGIN = 2, STATS = c(1, 3, 0, 2), FUN = "+")
print(data_ex3_b)```

This code produces a more reasonable output.

`     [,1] [,2] [,3] [,4][1,]    1    3    0    2[2,]    1    3    0    2[3,]    1    3    0    2[4,]    1    3    0    2[5,]    1    3    0    2[6,]    1    3    0    2`

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