You can interact with files present outside the R environment. R can read and write into various file formats like csv, excel, json, xml, binary etc.

CSV file

csv file is a text file where the column values are seperated by comma(,).

How to read a csv file

Consider sample.csv is present in the current working directory.

inp <- read.csv("sample.csv")
print(inp)

How to write to a csv file

write.csv(data,"filename.csv")

Excel file

R interacts with excel file using xlsx package.

Execute the below command to install xlsx package:

install.packages("xlsx")

To verify the xlsx package installed by using the below command:

any (grepl ("xlsx", installed.packages()))

How to read a excel file

inp <- read.xlsx("sample.xlsx", sheetIndex = 1)
print(inp)

Binary File

Binary file stores data in the form of 0's and 1's.

How to read a Binary file

readBin (conn, what, n )

How to write to a binary file

writeBin (object, conn)

• conn : connection object to read or write the binary file.
• object: Object is the binary file to be written.
• what: what is the mode like character, integer etc. representing the bytes to be read.
• n: number of bytes to read from the given binary file.

XML file

R interacts with XML file using xml package.

Execute the below command to install xlsx package:

install.packages("XML")

How to read a XML file

xmlParse() is used to read XML file in R.

data <- xmlParse(file = "sample.xml")
print(data)

MySQL Database

Execute the below command to install MySQL package.

install.packages("RMySQL")

Connecting to MySQL database

mysqlconn = dbConnect(MySQL(), user = 'root', password = '', dbname = 'dbname',
   host = 'localhost')

Querying database

dbSendQuery(mysqlconn, "database query")

you can use select/update/insert/delete queries in the above command.