# Frequently Asked Questions

Below are some frequently asked questions about the logr package. Click on the links below to navigate to the full question and answer content.

## Index

- Where is my log?
- How come it didn’t log anything?
- How do I change the name of the log?
- How do I add a timestamp to the log name?
- How do I log my code?
- How do I turn on symbolgen?
- How do I log environment variables and their values?
- How do I turn off the notes?
- How is put() different from log_print()?
- What are the “Base Packages” and “Other Packages” lines in the header?
- How can I get rid of the blank lines?
- How can I get rid of the traceback?
- Can I use logr in my own package?

## Content

### Where is my log?

Q: I followed the examples to add logr functions to my script, and I think I created a log. But I can’t find it. Where does the log go?

A: It depends on what you passed to the `file_name` parameter on the `log_open()` function.

If you passed nothing, the log will be created in a subdirectory named “log” in the same directory as your program, and with the program name.

If you passed a file name without a path, the log subdirectory will be created in your working directory, and the log will be named with the name you assigned it.

If you passed a full path, it will be created in the full path, but will still be created in a subdirectory named “log” unless the `logdir` parameter on `log_open()` is set to FALSE.

If you still can’t find it, add the following line to your program someplace after the call to `log_open()`:

    print(log_path())

Then rerun the program. The path to the log will be printed to the console.

Note that the `log_open()` function also returns the path to the log. You can save this path in a variable for easy access, like this:

    pth <- log_open()
    print(pth)

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### How come it didn’t log anything?

Q: I am able to create a log. But it doesn’t contain anything. Just a header and footer. How come nothing was logged?

A: The logr log is not a fully automatic log, such as a SAS® log. The primary way to get something logged is to log it explicitly with `log_print()` or `put()`. This is the only way to guarantee that something will be logged. Generally, if you want a complete log, it is best to sprinkle these functions liberally throughout the program, logging anything you feel is relevant.

The other way to get something to log is by using the autolog feature. This feature can be turned on in one of two ways:
1. Set the `autolog` parameter on the `log_open()` function to TRUE.
2. Set the “logr.autolog” option using an `options()` function, like so:

    options("logr.autolog" = TRUE)

The autolog feature will automatically log function calls from the dplyr, tidyr, and the sassy family of packages. It will not log Base R functions, or the functions from any other packages. It takes some experience to understand which functions will be automatically logged, and which will not.

To maximize the autolog feature, it is a best practice to use tidyverse functions, rather than the Base R equivalents. These functions stand a better chance of being logged automatically.

It is also a best practice to place a `put()` statement at the end of your dplyr pipelines. This is a very good habit to develop, and will greatly improve the quantity and quality of your logs. Here is an example:

    dat <- mtcars %>%
           subset(mpg < 20) %>%
           arrange(mpg) %>%
           put()

Note that the above `put()` statement has no effect on the resulting data frame. It simply logs the pipeline result before assigning it to the variable `dat`.

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### How do I change the name of the log?

Q: I have a log. But I don’t want the default name. How can I change it to something else?

A: The `file_name` parameter on the `log_open()` function controls the log name. You can set this parameter to be any log name you like. When the log is created, it will use the name set on this parameter. Example:

    log_open("MyCustomName.log")

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### How do I add a timestamp to the log name?

Q: I have an R program that runs on a schedule every day. I want to keep the logs from this program for a certain period of time. But logr always overwrites the log from the last run. Is there a way to get a datestamp on the log name, so it won’t overwrite?

A: You can append the datestamp to the log name on the `file_name` parameter. Like this:

    # Concatenate log name with datestamp
    nm <- paste0("mylog_", format(Sys.Date(), "%Y-%m-%d"))

    # Open log
    lf <- log_open(nm)

Then logr will not delete the previous day’s log.

If you want a full date and time stamp, adjust the codes on the `format()` function to your liking.

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### How do I log my code?

Q: In SAS® there is an option to log all the code in my program at the top of the log. I like this because it is a good record of my program at the time it was run. Is there a similar option in logr?

A: There is not an option, but there is a `log_code()` function that will allow you to accomplish the same thing. You just call the `log_code()` function at the point where you want the code logged. Normally this would be at the top of the program, after the call to `log_open()`. Like this:

    # Open log
    log_open("mylog.log")

    # Dump code to log
    log_code()

    # Continue program...

The above code will dump the entire program contents to the log. The code lines will be prefixed with a right arrow (“>”) to distinguish these lines from the rest of your log.

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### How do I turn on symbolgen?

Q: In SAS® there is an option called symbolgen that will log all the variable values in my program. This option is useful for debugging. Is there a similar option in logr?

A: Not really. You can log the values of individual variables by sending them to the log with a `put()` function. You can also log the entire environment with all variable values like this:

    # Open log
    log_open("test.log")

    # Write current variables to log
    put(ls().str())

    # Close log
    log_close()

Otherwise, it is better to debug R programs interactively. The interactive debugging features in R are much better than in SAS®. The logr log is geared more toward recording the execution of your program than debugging.

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### How do I log environment variables and their values?

Q: I want to write all the environment variables and their values to the logr log. Is there a way to do that?

A: There is no built-in feature to log the environment variables. But there is a Base R function `Sys.getenv()` that will retrieve the environment variables and their values. Then you can put them to the log like any other object:

    # Open log
    log_open("test.log")

    # Send environment variables to log
    put(Sys.getenv())

    # Close log
    log_close()

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### How do I turn off the notes?

Q: The notes are cluttering up my log, and are not providing anything that I need. I don’t need the elapsed time, etc. How can I turn them off?

A: The notes can be disabled in one of two ways:
1. Set the `show_notes` parameter on `log_open()` to FALSE.
2. Set the `logr.notes` option to FALSE using an `options()` function. Like this:

       options("logr.notes" = FALSE)

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### How is put() different from log_print()?

Q: There is another function `put()` that seems similar to `log_print()`. What is the difference between them?

A: There is no difference in functionality. `put()` is a direct alias of `log_print()`. The only difference is that `put()` is faster to type. It is also easy to remember for anyone who has used SAS® software. The `put()` function in the logr package does the same thing as the `%put()` function in SAS®. So this alias will warm the hearts of current/former SAS® programmers.

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### What are the “Base Packages” and “Other Packages” lines in the header?

Q: Recently I noticed the “Base Packages” and “Other Packages” lines show up in the log header. What are these lines? Are they supposed to have all my referenced packages? How come some are missing?

A: The “Base Packages” and “Other Packages” lines in the header are attempting to more fully describe the environment the program/script is running in. They are showing the packages that are installed and attached at the point the `log_open()` function was called.

The information from these lines is taken from Base R `sessionInfo()`, and shows a subset of information from that function. This information is being logged so that you have some record of the packages and versions that were in use at the time the script was ran. This is useful information if you need to recreate the output from a particular point in time.

Note that if you attach packages in the middle of the program, after the call to `log_open()`, these packages may not be recorded in the header. It is therefore best practice to place all of your `library()` calls at the top of your program, load up everything you need, and then call `log_open()`. This practice will help ensure that the header contains all the packages that are used by your program. This practice also makes your program easier to read, understand, and maintain.

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### How can I get rid of the blank lines?

Q: I want to remove the blank lines in the log, to make it as small as possible. I see there is a ‘blank_after’ parameter on `log_print()` to remove the blank line for a single log entry. But how can I get rid of all of them?

A: There is a parameter on the `log_open()` function called “compact” that will remove all the blank lines between log entries. Simply set compact = TRUE to remove all blank lines from the log. You may achieve the same result by setting the global option logr.compact = TRUE.

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### How can I get rid of the traceback?

Q: The traceback is dumping a huge amount of stuff into the log when there is an error. There is so much stuff, that I find this feature annoying and useless. How can I turn it off?

A: There is a parameter on the `log_open()` function called “traceback” that you can use to turn off the traceback messaging. Simply set traceback = FALSE. The global option logr.traceback = FALSE will do the same thing.

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### Can I use logr in my own package?

Q: I’m creating a package of functions for my company. I’d like to use the logr package to generate a log from my package. Is it possible to integrate logr into my package?

A: Yes. logr can be used for both direct and indirect logging from your own custom package. For more information, see the package integration vignette here.

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