R has two ways of representing missing data that are **NaN** and **Na**. The **NaN** means “**Not a Number**”, and it means there is a result, but it cannot be represented in the computer. The second is **NA **means **Not Available,** which means that the data is missing for unknown reasons. Let’s deep dive into NA in R.

**NA in R**

To represent the missing data in R, use the NA symbol. The **NA** stands for **Not Available**. NA is not a member of the IEEE standard for floating-point numbers. NA is a creation of R used to express a value that is not known as a placeholder.

**Use NA in vector to fill the missing values.**

Let’s define a vector with an NA value and use the **is.na()** function to check if which component has NA value, and in that case, it returns **TRUE** as a logical vector, other values will be **FALSE**.

```
rv <- c(11, NA, 18, 19, 21)
rv
is.na(rv)
```

**Output**

```
[1] 11 NA 18 19 21
[1] FALSE TRUE FALSE FALSE FALSE
```

As you can see that our second component of the vector contains an NA value.

### The test for missing values

To find the missing values in R, use the** is.na()** method, which returns the logical vector with **TRUE**. In our example,** is.na()** method returns **TRUE** to that second component, and all the others are **FALSE**.

**Using NA in Matrix to fill the missing values.**

Let’s fill the empty values of the matrix with NA values and see the output.

```
rv <- c(11, NA, 18, 19, 21, 46, NA, 29, 20)
mtrx <- matrix(rv, nrow = 3, ncol = 3)
mtrx
```

**Output**

```
[,1] [,2] [,3]
[1,] 11 19 NA
[2,] NA 21 29
[3,] 18 46 20
```

To check the NA values in Matrix, use the is.na() function.

```
rv <- c(11, NA, 18, 19, 21, 46, NA, 29, 20)
mtrx <- matrix(rv, nrow = 3, ncol = 3)
is.na(mtrx)
```

**Output**

```
[,1] [,2] [,3]
[1,] FALSE FALSE TRUE
[2,] TRUE FALSE FALSE
[3,] FALSE FALSE FALSE
```

**Apply mathematical operation to NA values**

If you add any numeric numbers to NA, then it will result in NA.

```
21 + NA
sqrt(NA)
NA + NA
```

**Output**

```
[1] NA
[1] NA
[1] NA
```

And we get the NA in all the outputs, but if we add **NA** + **NaN**, it will return **NaN**.

`NaN + NA`

**Output**

`[1] NaN`

**How to exclude NA values from the analysis**

If you are calculating a mean of vector and that vector contains NA values, then you can exclude that NA value and calculate the mean of remaining values. But if you don’t exclude the NA, then it will return NA in the output.

```
rv <- c(1, 2, NA, 4, 5)
mean(rv)
```

**Output**

`[1] NA`

To exclude the NA value, pass the **na.rm=TRUE** as a second parameter in the mean() function.

```
rv <- c(1, 2, NA, 4, 5)
mean(rv, na.rm = TRUE)
```

**Output**

`[1] 3`

That means it has a calculated mean of 4 values(1, 2, 4, 5) whose sum is 12 and mean is 3.

To remove the NA values from a vector, use the **na.omit()** function. The** na.omit()** method returns the object with listwise deletion of missing values.

```
rv <- c(1, 2, NA, 4, 5)
na.omit(rv)
```

**Output**

```
[1] 1 2 4 5
attr(,"na.action")
[1] 3
attr(,"class")
[1] "omit"
```

As you can see in the output that **NA** is omitted.

**Difference between NA and NaN in R**

**NaN** is different from **NA**. **NaN** implies a result that cannot be calculated for whatever reason or is not a floating-point number.

Numeric calculations whose result is undefined, such as ‘0/0’, give the **NaN** value. NA is usually interpreted as a missing value and has several modes including **NA_integer_ **and **NA_real_**.

**Conclusion**

If you are working with an external dataset then you often come across NA values and handle those values is a difficult task but using proper functions and methods, you can handle that value in an efficient manner. NA is more of a placeholder stating that it has a missing value. That is it for this NA value in the R tutorial.