The dim has a method for data frames, which returns the length of the **row.names** attribute of input data, and the length of input data is the numbers of “**rows**” and “**columns**”.

**dim() in R**

The dim() is an inbuilt R function that either sets or returns the dimension of the matrix, array, or data frame. The dim() function takes the R object as an argument and returns its dimension, or if you assign the value to the dim() function, then it sets the dimension for that R Object.

**Syntax**

```
# To get the dimension value
dim(data)
# To set the dimension value
dim(data) <- value
```

**Parameters**

The data is an input R Object whose dimension we have to get.

If we want to assign a new dimension, then use the second syntax.

**Example**

```
df <- data.frame(c1 = c("a", "b", "c", "d"),
c2 = c("e", "f", "g", "h"),
c3 = c("i", "j", "k", "l"),
c4 = c("m", "n", "o", "p"),
c5 = c("q", "r", "s", "t"))
df
cat("The dimension of data frame is: ", "\n")
dim(df)
```

**Output**

```
c1 c2 c3 c4 c5
1 a e i m q
2 b f j n r
3 c g k o s
4 d h l p t
The dimension of data frame is:
[1] 4 5
```

From the output, you can see that our data frame has (4, 5) dimensions. We have four rows and five columns.

For the data frame, the **`dim()`** function returns the number of rows and columns as an integer vector.

The functions **dim()** and **dim<-** are generic.

The simple versions of nrow and ncol could be defined as follows.

```
nrow0 <- function(x) dim(x)[1]
ncol0 <- function(x) dim(x)[2]
```

## Find the dimension of Vector in R

To find the dimension of the Vector, use the dim() function. The dimension of the vector always returns NULL.

```
rv <- c("u", "v", "w", "x")
cat("The dimension of Vector is: ", "\n")
dim(rv)
```

**Output**

```
The dimension of Vector is:
NULL
```

And it returns NULL. The dimension of the Vector in R is **NULL**.

To get the number of elements of the Vector, use the length() function.

**Set dimension of a matrix in R**

To set the dimension of the matrix, define a vector and use the dim() function to set the dimension.

```
rv <- rep(1:10)
rv
dim(rv) <- c(2, 5)
rv
```

**Output**

```
[1] 1 2 3 4 5 6 7 8 9 10
[,1] [,2] [,3] [,4] [,5]
[1,] 1 3 5 7 9
[2,] 2 4 6 8 10
```

We change the dimension from one dimension to multi-dimensions using the dim() function.

**How to find the dimension of Matrix in R**

To get the dimension of the matrix in R, use the **dim** attribute of the object.

```
rv <- 1:6
mtrx <- matrix(rv, 3, 2)
mtrx
dim(mtrx)
```

**Output**

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

## dim() of Array in R

To get the dimension of the array in R, use the dim() function.

```
arr <- array(1:24, dim = 2:4)
dim(arr)
```

**Output**

`[1] 2 3 4`

That is it for dim() function in the R Programming language.

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.