---
title: "Log Parts"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Log Parts}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r setup, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```

A **logr** log is composed of three parts:

#### Log Header
The log header provides an introduction to your log. The header block 
contains the path of the log file, the working directory, the name of the user,
a date-time stamp, and other useful information concerning the 
operating environment.  

#### Log Body 
The log body comprises the primary content of your log.  The body will
be populated with print-outs from the objects you send to the log with 
`log_print()`, `put()` and `sep()`.  The objects will be printed to the log
just as they are printed to the console.

Optional notes will be written to the log for every call to `log_print()` or 
`put()`. The notes 
will follow the printing of the object, and will include a date-time stamp
and the elapsed time since the last call. If the object
is of class `data.frame` the number of rows and columns will also be noted. 

Notes can be turned off with the `show_notes` parameter on `log_open()`, 
or by setting the global option `logr.notes` to FALSE.

#### Log Footer
The log footer concludes the log with another date-time stamp for the log
end time, and a total elapsed time for the entire script.  

Note that during
batch runs or when sourcing a script, the log
footer may not be generated if the script errors. Instead, the last line of 
the log will be the error message.

#### Example

Here is an example log showing each of the log parts described 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 
Base Packages: stats graphics grDevices utils datasets methods base
Other Packages: logr_1.2.7 dplyr_1.0.7 
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: [Additional Features](logr-features.html)