Explain separate_rows() Function in R with Examples

The separate_rows() function from the tidyr package is used to split the values in one or more columns into separate rows based on a specified delimiter. This function is especially helpful for datasets where a single column contains multiple values separated by delimiters such as commas or semicolons.

R separate_rows() Function

The separate_rows() function splits values in a column that are separated by a delimiter into individual rows, creating a tidy data structure where each row represents a single observation. You can specify the data type of the new row values using the convert parameter.

Syntax of separate_rows() Function

The general syntax of the separate_rows() function is’


# Syntax of the separate_rows()
separate_rows(data, cols, sep = "[^[:alnum:]]+", convert = FALSE)

Parameters

data: The input data frame or tibble.
cols: Column(s) to be separated into rows.
sep: The delimiter is used for splitting values. Default is a non-alphanumeric character.
convert: Logical value indicating whether to convert the new column values to their appropriate types (e.g., numeric, factor).

Return Value

The function returns a data frame or tibble with the specified columns split into multiple rows, with other columns remaining unchanged.

Separate Column Values Using R separate_rows()

In R, you can use the separate_rows() function to split values in a specified column into individual rows based on a delimiter (non-alphanumeric). Simply pass the column and the data frame as arguments to this function to separate the values in that column into distinct rows based on the delimiter.


# Split Column Values Using R separate_rows()
# Load tidyr package
library(tidyr)

# Create data frame
df <- data.frame(
  Student = c("Geetha", "Ram", "Priya"),
  Subjects = c("Math,Science", "Math,English", "Science,History")
)

print("Original Data Frame:")
print(df)

# Separate rows based on delimiter
sep_df <- separate_rows(df, Subjects, sep = ",")

print("After separating column values::")
print(sep_df)

Yields below output.

Separate Multiple Columns

You can also include multiple columns in the separate_rows() function to split their values into unique rows. Simply pass the desired columns along with the data frame to the function, and it will separate the values in those columns into individual rows based on the specified delimiter.


# Separate multiple columns
# Load tidyr package
library(tidyr)
# Create data frame
df <- data.frame(
  Student = c("Geetha", "Ram"),
  Subjects = c("Math,Science", "Math,English"),
  Activities = c("Debate,Music", "Sports,Art")
)

print("Original Data Frame:")
print(df)

# Separate rows for multiple columns
sep_df <- separate_rows(df, c(Subjects, Activities), sep = ",")

print("After separating Multiple Columns into rows:")
print(sep_df)

Yields below output.

Convert Type of New Values with convert Parameter

You can use the convert parameter of the separate_rows() function in R to handle the data type of the new values. Simply pass the columns you want to split, along with the data frame and the convert parameter. The function will automatically convert the new row values to their appropriate data types.


# Convert values to appropriate types
# Load tidyr package
library(tidyr)
# Create data frame
df <- data.frame(
  ID = c("1,2", "3,4"),
  Score = c("85,90", "75,80")
)

print("Original Data Frame:")
print(df)

# Separate rows and convert
sep_df <- separate_rows(df, c(ID, Score), sep = ",", convert = TRUE)

print("After converting the type of new values:")
print(sep_df)

# Output:
# [1] "Original Data Frame:"
#    ID Score
# 1 1,2 85,90
# 2 3,4 75,80

# [1] "After converting the type of new values:"
# # A tibble: 4 × 2
#      ID Score
#   <int> <int>
# 1     1    85
# 2     2    90
# 3     3    75
# 4     4    80

From the above output, numeric strings have been converted to numeric values.

Handle Empty Rows using R separate_rows()

To handle a column containing empty values, use the separate_rows() function effectively. By default, empty rows are retained, but you can filter them out if necessary.


# Handle empty values
# Load tidyr package
library(tidyr)
# Create data frame
df <- data.frame(
  Student = c("Geetha", "Ram"),
  Subjects = c("Math,Science", "")
)

print("Original Data Frame:")
print(df)

# Separate rows
sep_df <- separate_rows(df, Subjects, sep = ",")

print("Data Frame After separating rows:")
print(sep_df)

# Output:
# [1] "Original Data Frame:"

#   Student     Subjects
# 1  Geetha Math,Science
# 2     Ram 
# [1] "Data Frame After separating rows:"

# # A tibble: 3 × 2
#   Student Subjects 
#   <chr>   <chr>    
# 1 Geetha  "Math"   
# 2 Geetha  "Science"
# 3 Ram     ""

Frequently Asked Questions of separate_rows() function in R

What is the purpose of the separate_rows() function?

The function is used to split values in a column into separate rows based on a specified delimiter, making data tidy and easier to analyze.

How can I apply separate_rows() to multiple columns?

you can specify multiple columns to split simultaneously by passing their names to the cols parameter.

How do I handle missing or empty values?

By default, separate_rows() keeps rows with missing or empty values. You can filter them out manually if needed.

What happens if I don’t specify a delimiter?

If no delimiter is specified, separate_rows() uses the default regular expression [^[:alnum:]]+, which matches any non-alphanumeric character.

Conclusion

In this article, I explained the separate_rows() function of the tidyr package, a crucial tool for transforming columns with delimited values into tidy rows. Its ability to handle multiple columns, convert values, and manage empty entries makes it invaluable for data cleaning and preprocessing. By simplifying complex data formats, separate_rows() enhances the efficiency of data analysis workflows.

Happy Learning!

References

https://www.rdocumentation.org/packages/tidyr/versions/0.6.0/topics/separate_rows