There are different ways to import data in R depending on the source from which the data is to be imported.
Few of the sources are listed below:
1) Importing text and spreadsheets (read.table, sep, header, stringsasfactors)
Cmd line method:
Using GUI for data import:
2) Importing data of different statistical formats in R such as (foreign /SPSS, sas7bdat /SAS)
Using Data.table package
3) Configuring ODBC on Windows OS
Connecting to RDBMS using RODBC
4) Using SQLDF for SQL Queries in R
Using Sqlite in R
5) Web scraping (readlines, RCurl, XML)
JSON data
6) Reading Data from the Internet
Web Data from RGoogleAnalytics
7) NoSQL Databases (couchDB, MongoDB)
8) Introduction to Big Data Packages(ff, bigmemory, RevoScaleR)