Introduction

Using a Windows .bat file to execute an R script can be a convenient way to automate tasks and streamline your workflow. In this blog post, we will explain each line of a sample .bat file and its corresponding R script, along with a simple explanation of what each section does.

The .bat File:

@echo off

rem Set the path to the Rscript executable
set RSCRIPT="C:\Users\user\AppData\Local\Programs\R\R-4.2.3\bin\Rscript.exe"

rem Set the path to the R script to execute
set RSCRIPT_FILE="C:\Users\user\my_r_script.R"

rem Execute the R script
%RSCRIPT% %RSCRIPT_FILE%

rem Pause so the user can see the output
exit

Now, let’s break down each line:

@echo off: This line turns off the echoing of commands in the command prompt window, making the output cleaner.
rem Set the path to the Rscript executable: The rem keyword denotes a comment in a batch file. This line sets the path to the Rscript executable, which is the command-line interface for executing R scripts.
set RSCRIPT="C:\Users\user\AppData\Local\Programs\R\R-4.2.3\bin\Rscript.exe": This line assigns the path to the Rscript executable to the environment variable RSCRIPT.
rem Set the path to the R script to execute: This line is another comment, specifying that the next line sets the path to the R script that will be executed.
set RSCRIPT_FILE="C:\Users\user\my_r_script.R": Here, the path to the R script file is assigned to the environment variable RSCRIPT_FILE.
%RSCRIPT% %RSCRIPT_FILE%: This line executes the R script using the Rscript executable and passes the path to the R script file as an argument.
rem Pause so the user can see the output: This comment suggests that the script should pause after execution so that the user can view the output before the command prompt window closes.
exit: This command exits the batch file and closes the command prompt window.

The R Script:

The R script contains several sections. Here is the full script and then I will give an explanation of each section:

# Library Load
library(DBI)
library(odbc)
library(dplyr)
library(writexl)
library(stringr)
library(Microsoft365R)
library(glue)
library(blastula)

# Source SSMS Connection Functions 
source("C:/Path/to/SQL_Connection_Functions.r")

# Connect to SSMS
dbc <- db_connect()

# Query SSMS
query <- DBI::dbGetQuery(
  conn = dbc,
  statement = paste0(
    "
    select encounter,
        pt_no 
    from dbo.c_xfer_fac_tbl 
    where encounter in 
        (
        select distinct encounter
        from DBO.c_xfer_fac_tbl 
        group by encounter, file_name 
        having Count(Distinct pt_no) > 1
        ) 
        and INSERT_DATETIME = 
        (
        select Max(INSERT_DATETIME) 
        from dbo.c_xfer_fac_tbl
        ) 
    group by encounter, pt_no 
    order by encounter
    "
  )
)

db_disconnect(dbc)

# Save file to disk
path <- "C:/Path/to/files/encounter_duplicates/"
f_name <- "Encounter_Duplicates_"
f_date <- Sys.time() |> 
  str_replace_all(pattern = "[-|:]","") |>
  str_replace(pattern = "[ ]", "_")
full_file_name <- paste0(f_name, f_date, ".xlsx")
fpn <- paste0(path, full_file_name)

write_xlsx(
  x = query,
  path = fpn
)

# Compose Email ----
# Open Outlook
Outlook <- get_business_outlook()

email_body <- md(glue(
"
  ## Important!
  
  Please see attached file {full_file_name}
  
  The file attached contains a list of accounts from Hospital B
  that have two or more Hospital A account numbers associated with them. We therefore
  cannot process these accounts.
  
  Thank you,

  The Team
  "
))

email_template <- compose_email(
  body = email_body,
  footer = md("sent via Microsoft365R and The Team")
)

# Create Email
Outlook$create_email(email_template)$
  #set_body(email_body, content_type="html")$
  set_recipients(to=c("[email protected]", "[email protected]"))$
  set_subject("Encounter Duplicates")$
  add_attachment(fpn)$
  send()

# Archive File after it has been sent
archive_path <- "C:/Path/to/Encounter_Duplicate_Files/Sent/"
move_to_path <- paste0(archive_path, full_file_name)
file.rename(
  from = fpn,
  to = move_to_path
)

# Clear the Session
rm(list = ls())

Library Load: This section loads various R libraries needed for the script’s functionality, such as database connections, data manipulation, and email composition.
Source SSMS Connection Functions: Here, a separate R script file (SQL_Connection_Functions.r) is sourced. This file likely contains custom functions related to connecting to and querying a SQL Server Management System (SSMS) database.
Connect to SSMS: This line establishes a connection to the SSMS database using the db_connect() function.
Query SSMS: The script executes a SQL query against the SSMS database using the dbGetQuery() function. The result of the query is assigned to the query variable.
Save file to disk: The script saves the query result (query) to an Excel file on the local disk using the write_xlsx() function.
Compose Email: This section composes an email using the blastula package, preparing the email body and setting the recipients, subject, and

attachments.

Create Email: The composed email is created using the create_email() function from the Microsoft365R package. The body, recipients, subject, and attachment are set.
Send Email: The email is sent using the send() function, which relies on a connection to Microsoft Outlook. The email body, recipients, subject, and attachment are all included in the email.
Archive File after it has been sent: The script moves the Excel file to an archive folder after sending the email, using the file.rename() function.
Clear the Session: The rm() function is used to clear the current R session, removing any remaining objects from memory.

Conclusion

Using a Windows .bat file to execute an R script allows for easy automation and integration of R scripts into your workflow. By understanding each line of the .bat file and the corresponding R script sections, you can customize and adapt the process to suit your specific needs.