- Ekta Aggarwal

# Getting frequency distribution in R : Table function

In this tutorial we will learn how to get the frequency distribution in R using table function.

For this we will use R's inbuilt mtcars dataset which gives information about 32 cars. We can view the mtcars data using **View** function

`View(mtcars)`

**Frequency Distribution for one variable: **

Let us consider the variable am: which depicts whether the car is automatic or manual (0 = automatic, 1 = manual)

To understand how many automatic and manual cars are there we can use **table( ) **function. In table function we specify the categorical column for which we want the frequency distribution

`table(mtcars$am)`

__Output:__

**0 1 **

19 13

In the above output we can see that 19 is written below 0, which means there are 19 cars with am = 0. Similarly, 13 is written below 1, which means there are 13 cars with am = 1.

**Note: **table( ) function for a single column resulted in a vector. Thus, if we want to get the number of cases where am = 0, we can subset this vector, we writing either:

` table(mtcars$am)[1]`

or

`table(mtcars$am)["0"]`

In the first command we are subsetting the first element of the vector, while in the second command we are specifying that we are looking for am = "0".

*Note that in the second command we have to enclose the 0 by quotes " "*

**2-D Frequency Distribution: **

Let us say we want to see the frequency distribution for 2 categorical variables, thus for that use **table( ) **function.

Let us see consider the variables __cyl__, which tells us about the number of cylinders and __am __i.e, whether the car is automatic or manual (0 = automatic, 1 = manual)

`table(mtcars$am, mtcars$cyl)`

__Output:__

** 4 6 8**

**0 **3 4 12

**1** 8 3 2

In the above output we can see that there is now a 2X3 dataset, where 2 rows correspond to am= 0 and am = 1 and 3 columns are for cyl = 4,6, and 8.

We can see that for am = 0 and cyl = 4, we have 3 observations. Similarly, for am = 0 and cyl = 6 we have 4 observations.

**Note: **table( ) function for a 2 columns resulted in a dataframe. Thus, if we want to get the number of cases where am = 0, and cyl = 8 we can subset this vector, we writing either:

` table(mtcars$am, mtcars$cyl)[1,3]`

or

` table(mtcars$am, mtcars$cyl)["0","8"]`

In the first command we are subsetting the first row and third column of the dataframe, while in the second command we are specifying that we are looking for am = "0" and cyl = "8".

*Note that in the second command we have to enclose these by quotes " "*