# How to Fix in R: error in sort.int(x, na.last, decreasing, …) : ‘x’ must be atomic

One error message you may encounter when using R is:

```Error in sort.int(x, na.last = na.last, decreasing = decreasing, ...) :
'x' must be atomic
```

This error occurs when you attempt to sort a list.

By default, R is only capable of sorting atomic objects like vectors. Thus, to use sort() with a list you must first use the unlist() function.

The following example shows how to resolve this error in practice.

### How to Reproduce the Error

Suppose we have the following list in R:

```#create list
some_list <- list(c(4, 3, 7), 2, c(5, 12, 19))

#view list
some_list

[]
 4 3 7

[]
 2

[]
  5 12 19

#view class
class(some_list)

 "list"
```

Now suppose we attempt to sort the values in the list:

```#attempt to sort the values in the list
sort(some_list)

Error in sort.int(x, na.last = na.last, decreasing = decreasing, ...) :
'x' must be atomic
```

We receive an error because R is not capable of sorting lists directly.

### How to Avoid the Error

To avoid the error, we must first use the unlist() function as follows:

```#sort values in list
sort(unlist(some_list))

  2  3  4  5  7 12 19
```

Notice that we’re able to successfully sort the list of values without any error because we first used unlist(), which converted the list to a numeric vector.

By default, R sorts the values in ascending order.

However, we can use decreasing=TRUE to sort the values in descending order instead:

```#sort values in list in descending order
sort(unlist(some_list), decreasing=TRUE)

 19 12  7  5  4  3  2
```

Notice that the values are now sorted in descending order.