Error in sort.list(y) : ‘x’ must be atomic for ‘sort.list’

While the initial presentation of this error can be rather intimidating, the root cause is straightforward. In fact, it is basically a variant of another atomic vector related error we describe here.

To quote “The Bard”, the problem, Dear Brutus, is not in our stars but rather in our data structures. Specifically the data structures we are trying to sort or – in the related example – transform.

R has six atomic data structures (list of options here) which are generally referred to as vectors. These are locked down in terms of what they can contain and immutable. Think array, the C++ variety.

Lists in R, on the other hand, are far more flexible. For those C++ programmers out there, think linked list. Lists have elements, which can be attached to other elements and can contain any type of R object. Including, for that matter, other lists. Which in turn can contain other lists. And so on and so forth. In any event – think flexible. The whole entity is held together by the list structure, which is designed to be dynamically allocated (attach and remove list elements) and flexible with regards to its content.

Sorting – is not flexible. We’re taking a list of specific values and ranking them. I can rank numbers. I can rank letters. I can probably even rank logical variables. I cannot, however, rank lists. We need to reduce this down to something that R can easily look at and rank into the proper order.

This generally means unpacking the list using the “unlist” function and running the results through sort.

Fixing ‘x’ must be atomic for ‘sort.list’

A little spelunking in your code is likely in order. The essence of the issue is you’re feeding a non-atomic data type such as a list into a method which expects something a little simpler, ideally a vector.

Find the broken part of your process and use unlist() to unpack your information into a usable form.

The R programming language is a popular tool for statistical analysis and data visualization, often used by professionals in various industries. One common issue encountered by users is the error message: “Error in, na.last = na.last, decreasing = decreasing, …) : ‘x’ must be atomic”. As a part of the R code, the sort function plays a critical role in organizing data within dataframes, numeric vectors, and character vectors. Understanding the underlying cause of this error and how to address it is essential when working with functions like boxplot and data manipulation.

The primary reason behind this error is the presence of non-atomic vectors within a data structure being sorted. Atomic vectors include integer, logical, character, or factor data structures, and in R, it is essential to use these structures when applying the sort function. According to Statistics Globe, a common remedy for this issue is utilizing the unlist function to convert list elements into atomic vectors before sorting, thereby avoiding the error.

When working with dataframes and multiple columns, R users should be mindful of the variable types being sorted to ensure a proper ordering index vector is generated. Implementing methods like stable sorting, quicksort, and ordered factors can further aid in handling situations with missing values and ties, refining the sort order and returned values for complex data sets. As R programmers navigate through these challenges, staying informed on the best practices for data manipulation and error management is vital to maintaining efficiency and producing accurate results in the R environment.

Understanding the R Error

Error in Sort.intx

The error message “error in sort.intx: ‘x’ must be atomic” occurs because the input for the function in R must be an atomic vector. An atomic vector is a simple data structure in R that consists of elements of the same type, such as numeric, character, or logical values. If the input is a more complex data structure, such as a data frame or a list with multiple types of elements, this error may arise.

Na.last and Decreasing Parameters

Two important parameters in the function are “na.last” and “decreasing”. The “na.last” parameter specifies how to handle missing values (NA) in the input vector. If set to TRUE, NA values will be placed at the end of the sorted array, while setting it to FALSE will place NA values at the beginning. The default behavior is to place NA values at the end.

The “decreasing” parameter determines the sort order of the input vector. If set to TRUE, the vector will be sorted in descending order, while setting it to FALSE will result in an ascending order. By default, the sort function arranges the input vector in ascending order.

To resolve the “error in sort.intx: ‘x’ must be atomic” issue, ensure that the input is an atomic vector, such as a numeric, character, or logical vector. For example:

numeric_vector <- c(5, 2, 7, -1) 
sorted_num_vector <-, decreasing = TRUE) 

If the input is a data frame with multiple columns, you can either convert it into an atomic vector using the unlist function or use other R functions such as order or with to handle sorting specific columns. For example, to sort a data frame by a numeric column:

data_frame <- data.frame( name = c("Alice", "Bob", "Carol"), age = c(28, 32, 24) ) 
ordered_data_frame <- data_frame[order(data_frame$age, decreasing = TRUE), ] 

By following these guidelines, you can effectively resolve the R error related to the function and successfully sort your data structures.

Dealing with Different Data Structures

The R error in, na.last = na.last, decreasing = decreasing, ...) that states ‘x’ must be atomic typically occurs when dealing with different data structures that are not suitable for sorting. In this section, we will discuss how to handle various data structures in R, such as atomic vectors, data frames, character vectors, logical vectors, and integer vectors to avoid this error.

Atomic Vector

An atomic vector is a fundamental data structure in R that stores elements of the same type. To sort an atomic vector, use the sort() function. For example:

numeric_vector <- c(10, 2, 5, 8, 1)
sorted_vector <- sort(numeric_vector)

When sorting atomic vectors with missing values, use the na.last = TRUE option in sort() to put NA values at the end:

vector_with_na <- c(3, NA, 6, 2, 8, NA)
sorted_vector <- sort(vector_with_na, na.last = TRUE)


To sort a dataframe, you can use the order() function. First, extract the column of interest and apply the order() function to obtain an index vector, then sort the dataframe based on this index:

data <- data.frame(a = c(3, 1, 2), b = c("A", "C", "B"))
sorted_data <- data[order(data$a), ]

Character Vector

To sort a character vector, apply the sort() function in the same manner as an atomic vector:

char_vector <- c("apple", "orange", "banana")
sorted_char_vector <- sort(char_vector)

Logical Vector

Sorting logical vectors (TRUE/FALSE) also requires the sort() function:

logical_vector <- c(TRUE, FALSE, TRUE, FALSE)
sorted_logical_vector <- sort(logical_vector)

Integer Vector

An integer vector can be treated like a numeric vector and sorted using the sort() function:

integer_vector <- c(4L, 2L, 9L, 1L)
sorted_integer_vector <- sort(integer_vector)

By understanding and properly handling these different data structures in R, you can prevent the ‘x’ must be atomic error when using the function.

Sorting Techniques in R

In this section, we will discuss various sorting techniques in R, focusing on partial sorting, stable sort, and quicksort algorithms.

Partial Sorting

Partial sorting in R is a technique that allows you to sort only a part of the data. This can be useful when you need to find the smallest or largest elements in a dataset. One way to achieve partial sorting in R is by using the sort() function with the partial argument.

For example, if you want to sort a numeric vector and find the five smallest values, you can use the following R code:

numeric_vector <- c(5, 3, 9, 1, 6)
sorted_values <- sort(numeric_vector, partial = 1:5)

Stable Sort

A stable sort is a sorting algorithm that maintains the relative order of elements with equal values. In R, the order() function can provide a stable sorting by taking into account multiple columns or factors, such as sorting a dataframe by more than one column.

For example, let’s say we have the following dataframe:

data_frame <- data.frame(Name = c("Alice", "Bob", "Cathy", "David", "Eva"),
Age = c(28, 34, 28, 29, 22),
Score = c(85, 74, 95, 78, 91))

To sort the dataframe by age and then by score (in case of ties), you can use the following R code:

sorted_dataframe <- data_frame[order(data_frame$Age, data_frame$Score),]


Quicksort is a well-known sorting algorithm that is considered efficient for large datasets. In R, the sort() function uses quicksort as its default sorting method for most data types.

For example, to apply quicksort on a numeric vector, you can use the following R code:

numeric_vector <- c(3, 7, 1, 4, 6)
sorted_vector <- sort(numeric_vector)

To conclude, understanding different sorting techniques in R, such as partial sorting, stable sort, and quicksort, can help you manipulate data more effectively and find relevant information needed for your analysis or visualization tasks.

Handling Missing Values and Ordered Factors

In this section, we will discuss how to handle missing values and ordered factors while dealing with the R error in, na.last = na.last, decreasing = decreasing, …): ‘x’ must be atomic. This error occurs when attempting to sort a non-atomic vector, such as a list, using the function in R.

Handling Missing Values

Missing values in R are typically represented as NA. When sorting a vector or dataframe that contains missing values, it is essential to handle them properly. The sort function in R provides the argument na.last to control the placement of missing values in the sorted result. By default, na.last=TRUE, placing all NAs at the end of the sorted vector or dataframe(Statistics Globe).

To illustrate the handling of missing values, consider the following example with a numeric vector containing missing values:

# Sample numeric vector containing NAs 
x <- c(3, 5, NA, 2, NA, 9) 

# Sorting the vector while placing all NAs 
last sorted_x <- sort(x, na.last = TRUE)

In this example, the sorted_x vector will have the missing values at the end, i.e., (2, 3, 5, 9, NA, NA).

Ordered Factors

Factors are categorical variables in R that can either be unordered or ordered. When working with ordered factors, it is necessary to ensure that the sorting function considers the order of the levels properly. To sort an ordered factor, just use the sort function directly, as it automatically takes the order of the levels into account. However, if you want to sort a dataframe based on multiple columns that include ordered factors, you should use the order function to create an ordering index vector(Stack Overflow).

For instance, consider the following example with ordered factors:

# Sample dataframe containing ordered factors 
df <- data.frame(id = c(1, 2, 3, 4, 5), grade = factor(c("B", "A", "C", "A", "B"), levels = c("A", "B", "C"), ordered = TRUE)) 

# Sorting the dataframe based on the grade column 
sorted_df <- df[order(df$grade),]

In this example, the sorted_df dataframe is sorted based on the “grade” column while considering the order of the factor levels “A”, “B”, and “C”.

Sorting by Multiple Columns and Variable Order

In the R programming language, it is essential to ensure that data is cleaned and manipulated in a way that makes it easy to analyze. One common operation is sorting data based on multiple columns and variable order. This section will describe how to sort data in R using different criteria and taking into account possible error sources.

Multiple Columns

To sort a data frame by multiple columns, the order() function can be used in combination with the [ indexing operator. For example, to sort a data frame with columns A and B, you can use the following code:

sorted_data <- data[order(data$A, data$B), ]

This will generate a new data frame sorted by the specified columns in ascending order. Keep in mind that an error in sort.intx may arise if the variable passed to the order() function is not an atomic vector. An atomic vector can be any one of the following: logical, integer, numeric, complex, character, or raw.

Variable Order

The order of sorting can be adjusted using the decreasing parameter in the order() function. To sort the data frame by column A in ascending order and column B in descending order, follow this code:

sorted_data <- data[order(data$A, -data$B), ]

This will sort the data frame first by column A in ascending order and then by column B in descending order. Although the order() function can handle missing values with the na.last argument, consider using the na.omit() function to remove rows with missing data before performing any data manipulation tasks.

In conclusion, sorting data by multiple columns and variable order is a crucial step in data manipulation using the R programming language. Ensure that you use the appropriate functions and parameters, such as order()decreasing, and na.last, and guarantee that the passed variables are atomic vectors to prevent potential errors.

R Functions for Sorting

In this section, we will discuss various R functions used for sorting data, including the Sort Function, Order Function, and Sort Order. These functions are essential for organizing data in R, making it easier to analyze and visualize.

Sort Function

The sort() function is a basic R function to sort a vector. It can be used with numeric, character, logical, and factor vectors. The default behavior is to sort the elements in ascending order. The function can also handle missing values (NA) properly. Here’s an example of using the sort() function with a numeric vector:

numeric_vector <- c(5, 2, 8, 1, 7) sorted_numeric <- sort(numeric_vector)

The above code snippet sorts a numeric vector in ascending order. The sort() function can also be applied to a character vector:

character_vector <- c("apple", "orange", "banana", "grapes") sorted_character <- sort(character_vector)

Order Function

The order() function in R programming returns an integer vector representing the ordering index of the elements. This is especially useful when dealing with data frames or sorting multiple columns in a dataframe. Here’s an example:

data_frame <- data.frame(Name = c("John", "Peter", "Sam", "David"), Age = c(28, 34, 26, 31)) 
ordered_data <- data_frame[order(data_frame$Age),]

The above code snippet sorts the data frame based on the Age column in ascending order.

Sort Order

In R, the rank() function can be used to obtain the sort order for different types of data. This function ranks the elements in a vector, assigning values ‘1’ to the smallest element, ‘2’ to the second smallest, and so on. The rank() function can also deal with ties and missing values (NA). Here’s an example:

numerical_vector <- c(8, 3, 9, 4, 2) 
ranked_numerical <- rank(numerical_vector)

The code above ranks the elements in the numeric vector with ‘1’ for the smallest value (2) and ‘5’ for the largest value (9).

These functions, such as the sort() and order() functions, help to handle different types of data, allowing for easier data analysis in R programming. As seen in the examples provided, these functions can be applied to a variety of data structures, such as numeric vectors, character vectors, logical vectors, and data frames. By using these functions efficiently, you can effectively manage and analyze data in R. Remember to consider factors like missing values and data types when using sorting functions in R.

Tie-Breaking and Error Handling

In this section, we will discuss two important aspects to consider when working with sorting in R: tie-breaking and error handling. We will first explore different methods for breaking ties in sorting algorithms and then dive into common error handling techniques for addressing the “error in, na.last = na.last, decreasing = decreasing, …) : ‘x’ must be atomic” issue.


When sorting data in R, you may come across situations where two elements have equal values, and a tie-breaking method is needed. In such cases, you can use the order() function along with the data.frame() function to sort the data by multiple columns. The order() function generates an ordering index vector that specifies the order of elements in the input vector.

Here’s an example of using order() function for tie-breaking:

data_half <- data.frame(col1 = c(3, 1, 3, 2, 1, 2), col2 = c(50, 83, 30, 33, 21, 52)) 
sorted_data <- data_half[order(data_half$col1, data_half$col2), ]

This code snippet sorts the data frame by ‘col1’ first and then by ‘col2’, ensuring that any ties are handled appropriately.

Error Handling

A common error encountered when using the sort function in R is “error in, na.last = na.last, decreasing = decreasing, …) : ‘x’ must be atomic.” This error occurs when the input ‘x’ is a non-atomic vector or not supported by the sort function. The sort() function works only with atomic vectors (numeric, character, or logical).

In order to handle this error, you can follow these steps:

  1. Check the type of the input ‘x’ using the class() function.
  2. If ‘x’ is a list, convert it to an atomic vector using the unlist() function before sorting.
  3. If ‘x’ is a data frame, convert it to a numeric or character vector before sorting.

Here’s an example of how to handle this error:

unlist_object <- unlist(list_object, recursive = TRUE) 
sorted_atomic_vector <- sort(unlist_object)

This code snippet converts the list object to an atomic vector using the unlist() function and then sorts it using the sort() function.

Common R Methods and Packages

In this section, we will discuss common R methods and packages that are useful for solving the R error in, na.last = na.last, decreasing = decreasing, …) : ‘x’ must be atomic. This error often occurs when attempting to sort a non-atomic vector, such as a list or a data frame, in R programming language.

Unlist Function

The unlist function can be used to convert a non-atomic vector, such as a list or data frame, into an atomic vector before sorting. This function simplifies the input object, preserving the elements’ values, and consolidating them into a single vector. An example of how to utilize the unlist function in R code is shown below:

input_list <- list(a = c(4, 6, 2), b = c(7, 1, 5)) 
atomic_vector <- unlist(input_list) 
sorted_vector <- sort(atomic_vector)

In this example, we first create a list called input_list containing two character vectors. By using the unlist function, we are able to convert the list into an atomic vector, which can then be easily sorted using the sort function.

Data Structures Packages

Several data structures packages can assist in addressing the ‘x’ must be atomic error, such as dplyr and data.table. These packages contain functions tailored for handling data frames and provide efficient sorting methods for various data types, including numeric vectors, character vectors, and factors.

The dplyr package, for example, offers the arrange function which allows sorting of data frames by multiple columns, handling missing values (NA’s) and providing stable sort order for ties. Here’s an example using dplyr:

data_frame <- data.frame(column1 = c(4, 6, 2, 7, 1, 5), column2 = c("A", "B", "C", "D", "E", "F")) 
sorted_data_frame <- data_frame %>% arrange(column1, column2)

In this example, we first load the dplyr package and create a data frame with two columns. We then use the arrange function to sort the data frame by both columns in ascending order.

In conclusion, using appropriate methods such as the unlist function, and leveraging specialized packages like dplyr and data.table, can help to address the ‘x’ must be atomic error in R by facilitating the appropriate sorting of various data structures.

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