The rowSums() function calculates the sum of each row of a numeric array, matrix, or data frame. The colMeans() function calculates the mean of each column of a numeric array, matrix, or data frame. The rowMeans() function calculates the mean of each row of a numeric data frame, matrix, or array.

**colSums in R**

The colSums() is a built-in R function that calculates the sum of a column. The colSums() function takes an R object like an array of two or more dimensions and returns the sum of the columns.

The colSums() function calculates the sum of each column of a numeric data frame, matrix, or array. It forms the row and column sums and means for numeric arrays (or data frames).

**Syntax**

`colSums(x, na.rm = FALSE, dims = 1)`

**Parameters**

**x:** It is an array of two or more dimensions, containing numeric, complex, integer, or logical values, or a numeric data frame.

**na.rm**: It is logical. Should missing values (including NaN) be omitted from the calculations.

**dims: **It is an integer: Which dimensions are regarded as ‘**rows**’ or ‘**columns**’ to sum over.

**Example**

To create a matrix in R, use the matrix() function. We will use the rep() function to create a vector and then use the matrix() function to create a matrix function.

```
mtrx <- matrix(rep(1:4), 2, 2)
mtrx
```

**Output**

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

Now, use the colSums() function to calculate the sum of column values of the matrix.

```
mtrx <- matrix(rep(1:4), 2, 2)
mtrx
cat("The sum of columns is: ", "\n")
colSums(mtrx)
```

**Output**

```
[,1] [,2]
[1,] 1 3
[2,] 2 4
The sum of columns is:
[1] 3 7
```

**Finding the sum of column values of the 3D array.**

To create a 3D array, use the array() function. Then, use the colSums() function to calculate the sum of columns of the array.

```
arr <- array(1:12, c(2, 3, 3))
arr
cat("The sum of columns is: ", "\n")
colSums(arr)
```

**Output**

```
, , 1
[,1] [,2] [,3]
[1,] 1 3 5
[2,] 2 4 6
, , 2
[,1] [,2] [,3]
[1,] 7 9 11
[2,] 8 10 12
, , 3
[,1] [,2] [,3]
[1,] 1 3 5
[2,] 2 4 6
The sum of columns is:
[,1] [,2] [,3]
[1,] 3 15 3
[2,] 7 19 7
[3,] 11 23 11
```

**Calculating the sum of column values in R Data Set**

You can use the inbuilt R dataset like **ChickWeight** and calculate the sum of its column values. But, first, let’s get the snapshot of the **ChickWeight** dataset using the **head() **function.

`head(USArrests, 5)`

**Output**

```
Murder Assault UrbanPop Rape
Alabama 13.2 236 58 21.2
Alaska 10.0 263 48 44.5
Arizona 8.1 294 80 31.0
Arkansas 8.8 190 50 19.5
California 9.0 276 91 40.6
```

We will use the colSums() function to calculate the sum of **Murder, Assult, UrbanPop, **and **Rape **column values.

`colSums(USArrests)`

**Output**

```
Murder Assault UrbanPop Rape
389.4 8538.0 3277.0 1061.6
```

That is it for colSums() function in R.

**See also**

Calculate the square of Number in R

Krunal Lathiya is an Information Technology Engineer by education and web developer by profession. He has worked with many back-end platforms, including Node.js, PHP, and Python. In addition, Krunal has excellent knowledge of Data Science and Machine Learning, and he is an expert in R Language. Krunal has written many programming blogs, which showcases his vast expertise in this field.