# Calculate the Mean of each Column of a Matrix or Array in R Programming – colMeans() Function

Last Updated : 03 Jun, 2020

`colMeans()` function in R Language is used to compute the mean of each column of a matrix or array.

Syntax: colMeans(x, dims = 1)

Parameters:
x: array of two or more dimensions, containing numeric, complex, integer or logical values, or a numeric data frame
dims: integer value, which dimensions are regarded as â€˜columnsâ€™ to sum over. It is over dimensions 1:dims.

Example 1:

 `# R program to illustrate ` `# colMeans function ` ` `  `# Initializing a matrix with ` `# 3 rows and 3 columns ` `x <``-` `matrix(rep(``1``:``9``), ``3``, ``3``) ` ` `  `# Getting matrix representation ` `x ` ` `  `# Calling the colMeans() function ` `colMeans(x) `

Output:

```     [, 1] [, 2] [, 3]
[1, ]    1    4    7
[2, ]    2    5    8
[3, ]    3    6    9

[1] 2 5 8
```

Example 2:

 `# R program to illustrate ` `# colMeans function ` ` `  `# Initializing a 3D array ` `x <``-` `array(``1``:``12``, c(``2``, ``3``, ``3``)) ` ` `  `# Getting the array representation ` `x ` ` `  `# Calling the colMeans() function ` ` `  `# for dims = 1, x[, 1, 1], x[, 2, 1], x[, 3, 1], ` `# x[, 1, 2] ... are columns ` `colMeans(x, dims ``=` `1``) ` ` `  `# for dims = 2, x[,,1], x[,,2], x[,,3] ` `# are columns ` `colMeans(x, dims ``=` `2``) `

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

[, 1] [, 2] [, 3]
[1, ]  1.5  7.5  1.5
[2, ]  3.5  9.5  3.5
[3, ]  5.5 11.5  5.5

[1] 3.5 9.5 3.5
```

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