# colSums in R: How to Use colSums() Function in R

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
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.