# How to Put margins on tables or arrays in R

How to Put margins on tables or arrays in R, We’ll show you how to use the addmargins function in R to add margins to tables or arrays.

The tutorial will include two examples of using the addmargins function to annotate margin values on table objects.

Let’s get this party started:

## How to Put margins on tables or arrays in R

```data <- data.frame(x1 = c(LETTERS[1:3],
"B", "B", "C")
x2 = letters[1:2])
data                                         ```
```   x1 x2
1  A  a
2  B  b
3  C  a
4  B  b
5  B  a
6  C  b```

Examine the preceding table. It shows that the example data frame has six rows and two variables.

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Based on these data, we can then create a table object (i.e. a contingency table).

```tab <- table(data)
tab                                       ```
```x2
x1  a b
A 1 0
B 1 2
C 1 1```

The preceding RStudio console output shows our table without margins.

### Example 1: Assign Sum Margins to a Contingency Table Using the function addmargins()

Example 1, Will show how to use the addmargins function to add the sum of each row and column to a table’s margins.

Consider the R code below:

```tab_sum <- addmargins(tab, FUN = sum)
tab_sum                                      ```
```x2
x1    a b sum
A   1 0   1
B   1 2   3
C   1 1   2
sum 3 3   6```

As you can see, we have annotated another row and column with our data’s sum margins.

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### Example 2: Assign Mean Margins to a Contingency Table Using the function addmargins()

We used the sum function in Example 1 to add margins to our contingency table.

However, other functions within the addmargins command can be used.

The R code below demonstrates how to annotate mean values to a table object:

```tab_mean <- addmargins(tab, FUN = mean)
tab_mean                                    ```
```x2
x1       a   b mean
A    1.0 0.0  0.5
B    1.0 2.0  1.5
C    1.0 1.0  1.0
mean 1.0 1.0  1.0```

The previous table has the same structure as Example 1. However, instead of sum margins, we have included mean margins this time.

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