A log4j derivative for R.
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The log4r package is meant to provide a clean, lightweight object-oriented approach to logging in R based roughly on the widely emulated log4j API. The example code below shows how the logger is used in practice to print output to a simple plaintext log file.


  • Stable CRAN version:

  • Development version on GitHub:


Example Code

# Import the log4r package.

# Create a new logger object with create.logger().
logger <- create.logger()

# Set the logger's file output: currently only allows flat files.
logfile(logger) <- file.path('base.log')

# Set the current level of the logger.
level(logger) <- "INFO"

# Try logging messages at different priority levels.
debug(logger, 'A Debugging Message') # Won't print anything
info(logger, 'An Info Message')
warn(logger, 'A Warning Message')
error(logger, 'An Error Message')
fatal(logger, 'A Fatal Error Message')

The log4r Priority Levels

log4r supports five priority levels. In order from lowest to highest priority, they are:

  • "DEBUG"
  • "INFO"
  • "WARN"
  • "ERROR"
  • "FATAL"

Keep in Mind

  • Calling logfile(logger) <- file.path('logs', 'my.log') will fail if the logs directory does not already exist. In general, no effort is made to create non-existent directories.
  • Only messages at or above the current priority level are logged. Messages below this level are simply ignored.
  • Using the internal priority level constants using the ::: notation is deprecated, but no warning is given. It is safer to simply use strings or numeric constants.

Future Changes

  • create.logger() will become a singleton method to insure log integrity.
  • Future versions of log4r will respect the format attribute of logger objects.