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Standardize a List-Column in a Data Frame

standardize_list_column.Rd

This function standardizes a specified list-column in a data frame, ensuring that all elements within the column have a consistent structure. It is particularly useful when dealing with data frames containing nested lists or data frames that may have inconsistent structures due to data serialization or deserialization processes.

Usage

standardize_list_column(data, column_name)

Arguments

data

A data frame containing the list-column to standardize.

column_name

A string specifying the name of the list-column to standardize.

Value

A data frame with the specified list-column standardized, ready for unnesting.

Details

The function iterates over each element of the specified list-column and standardizes its structure as follows:

  • If an element is a data frame, it remains unchanged.

  • If an element is an empty list (i.e., list()), it is converted to NULL.

  • If an element is a list containing a single data frame, it extracts and returns that data frame.

  • If an element is a list of multiple data frames, it combines them into a single data frame using dplyr::bind_rows().

  • If an element is NULL, it remains NULL.

  • Any other types of elements are set to NULL.

This standardization ensures that the list-column can be unnested without errors, facilitating consistent data processing and analysis.

See also

bind_rows, unnest

Examples

if (FALSE) { # \dontrun{
# Load necessary libraries
library(dplyr)
library(tidyr)

# Sample data frame with inconsistent 'gillnets' column
core_data <- data.frame(
  submission_id = c(1, 2, 3),
  gillnets = list(
    data.frame(gillnet_length = 100, gillnet_mesh = 50), # Data frame
    list(data.frame(gillnet_length = 150, gillnet_mesh = 60)), # List containing a data frame
    list() # Empty list
  ),
  stringsAsFactors = FALSE
)

# Apply the function to standardize the 'gillnets' column
core_data <- standardize_list_column(core_data, "gillnets")

# Unnest the 'gillnets' column
gillnets_data <- core_data %>%
  select(submission_id, gillnets) %>%
  unnest(gillnets, keep_empty = TRUE)

# View the result
print(gillnets_data)
} # }