The logr package helps create log files for R scripts. The package provides easy logging, without the complexity of other logging systems. It is designed for analysts who simply want a written log of their program execution. The package is implemented as a wrapper to the base R sink() function.

How to use

There are really only three logr functions:

The log_open() function initiates the log. The log_print() function prints an object to the log. The log_close() function closes the log. In normal situations, a user would place the call to log_open() at the top of the program, call log_print() as needed in the program body, and call log_close() once at the end of the program.

A sample program is as follows:

library(logr)

# Create temp file location
tmp <- file.path(tempdir(), "test.log")

# Open log
lf <- log_open(tmp)

# Send message to log
log_print("High Mileage Cars Subset")

# Perform operations
hmc <- subset(mtcars, mtcars$mpg > 20)

# Print data to log
log_print(hmc)

# Close log
log_close()

# View results
writeLines(readLines(lf))

What to print to the log

You can print to the log anything that you can print to the console: vectors, lists, and data frames are all valid objects for logging. Under the hood, logr calls the print() function on that object, and writes the results to the log. The log_print() function, by default, will also print the object to the console. That means you can replace calls to print() with log_print(), and there will be no loss of convenience during development.

What the log looks like

The log created by logr is simpler than most logging packages. This log is designed to be human-readable, and increases the traceability of your activities. There are three main enhancements to a logr log:

  • A log header
  • Notes
  • A log footer

Here is an example log, created by the sample program above:

========================================================================= 
Log Path: C:/Users/dbosa/AppData/Local/Temp/RtmpQtOzhy/log/test.log 
Working Directory: C:/packages/logr 
User Name: dbosak 
R Version: R Under development (unstable) (2020-06-29 r78751) 
Machine: BOSAK-MAIN x86-64 
Operating System: Windows 10 x64 build 18362 
Log Start Time: 2020-06-30 07:15:52 
========================================================================= 

High Mileage Cars Subset 

NOTE: Log Print Time:  2020-06-30 07:15:52 
NOTE: Elapsed Time in seconds: 0.0219531059265137 

                mpg cyl  disp  hp drat    wt  qsec vs am gear carb
Mazda RX4      21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag  21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
Datsun 710     22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
Hornet 4 Drive 21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
Merc 240D      24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
Merc 230       22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2
Fiat 128       32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
Honda Civic    30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
Toyota Corolla 33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
Toyota Corona  21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
Fiat X1-9      27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
Porsche 914-2  26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
Lotus Europa   30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
Volvo 142E     21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2

NOTE: Data frame has 14 rows and 11 columns. 

NOTE: Log Print Time:  2020-06-30 07:15:52 
NOTE: Elapsed Time in seconds: 0.0508558750152588 

========================================================================= 
Log End Time: 2020-06-30 07:15:53 
Log Elapsed Time: 0 00:00:00 
========================================================================= 

Next Steps

For addition exploration of the logr package, please read the following articles: