Write an R List to a JSON File

Takes a named R list and writes it to a JSON file.

Usage

write_list_to_json(data_list, file_path, compress = FALSE)

Arguments

data_list

A named list containing the data to write.

file_path

A character string specifying the full file path for the output JSON file.

compress

Logical. If TRUE, the JSON is written in gzipped format and the file extension is forced to .json.gz. Default is FALSE.

Value

This function does not return a value. It prints a message indicating that the file was successfully written.

Details

The function converts the R list to JSON text using jsonlite::toJSON() (with pretty printing enabled) and then writes it out either to a plain text file or to a gzipped file if compress = TRUE. The gzipped file is created using a connection opened with gzfile(). Numbers are written with 17 significant digits, enough to round-trip every double exactly, so a config read back from the file reproduces a simulation bit for bit. The text is written to a temporary file in the target directory and then renamed over file_path, so an interrupted write never leaves a truncated file behind.

Examples

if (FALSE) { # \dontrun{
  sample_data <- list(
    group1 = list(
      value1 = rnorm(100),
      value2 = runif(100)
    ),
    group2 = list(
      message = "Hello, MOSAIC!",
      timestamp = Sys.time()
    )
  )

  # Write to a plain JSON file.
  output_file <- "output.json"
  write_list_to_json(data_list = sample_data, file_path = output_file, compress = FALSE)

  # Write to a gzipped JSON file.
  output_file_gz <- "output.json"  # Note: the function will change this to output.json.gz
  write_list_to_json(data_list = sample_data, file_path = output_file_gz, compress = TRUE)

  # Load the plain JSON file to inspect its contents.
  json_data <- jsonlite::read_json(output_file)
  print(json_data)
} # }