Reading data into r

Reading Structured Data into R
Srikanth Potukuchi
Analytics Consultant
srikanth.potukuchi@gmail.com
April 21, 2018
Srikanth Potukuchi (Consultant Analytics) Reading Data April 21, 2018 1 / 26

Overview
1 Introduction
2 Delimited Files
3 Excel Files
4 Reading from Database
5 Data from Other Statistical Tools
6 Getting Website Data
7 Summary

Introduction
Introduction-Focus on Structured Data
Data comes in many forms: Structured and UnStructured. In this
deck, we are focusssing on Structured Data-which is basically in the form
of rows and columns (Also known as Tabular Data).
We will look at reading delimited files(CSV, Tab, Special
delimiters), excel files, database(MS Access and Oracle), data from other
Statistical tools like SAS, SPSS, Stata, Octave, Minitab,and Systat; and
finally we will look at extracting data from Websites as well.

Introduction
Introduction-Installing Packages
Installing a package in R can be done using install.packages(“Your
Package Name”) and except for the built-in Base package- other packages
have to be loaded using library(Your Package Name) or require(Your
Package Name). Here’s an example:
>install.packages(‘‘RODBC ’’)
>library(RODBC)

Introduction
Data Included with R.
Suppose we install a package- say ggplot2.
What datasets are included in this package?

Delimited Files
Delimited Files-Comma Separated File (CSV)
CSV ﬁles are mostly read using read.csv() or read.csv2(). The
diﬀerence between the two is the default separator and decimal point. The
basic syntax is:
>read.csv(file ,header=TRUE , sep=",",quote=""",
dec=".",fill=TRUE ,comment.char="" ,...)
>read.csv2(file ,header=TRUE ,sep=";",quote=""",
dec=",",fill=TRUE ,comment.char="" ,...)

Delimited Files
Large CSV ﬁles are mostly read using read.table(). The basic
syntax is:
>read.table(file ,header=FALSE , sep="",quote=""",
dec=".",stringsAsFactors =default. stringsAsFactors () ,...)
Reading CSV ﬁle from a website

Delimited Files
The result of using read.table is a data.frame. The path will give an
error if forward slash or double slash is not used.
Reading CSV ﬁle locally

Excel Files
Excel Files
Difficult to read excel data into R
Simplest method convert the Excel file to a CSV file.
Packages to address this problem:
Gdata
XLConnect
xlsReadWrite
Reading Excel file locally-set the path

Excel Files
Excel Files
Use the function readWorksheetFromFile

Reading from Database
To read from databases like Microsoft SQL Server,DB2, MySQL,
Oracle SQL or Microsoft Access we must provide an ODBC
connection.
We need RODBC package to use ODBC in R.
First Step is to create a DSN which diﬀers by OS.
ODBC Connection

Download necessary drivers if not present here:

Reading from MS Access Database
Add the data source:

Reading from MS Access Database
Use odbcConnect() function:
Use sqlQuery() function:

Reading from Oracle Database
Use this Link for details on reading from Oracle Database.:

Data from Other Statistical Tools
Data from Other Statistical Tools
List of Packages and Functions:
Reading fromSystat:

Getting Website Data
Simple HTML Tables
Use XML package:

Simple HTML Tables
Use readHTMLTable function:

Use Regular Expressions to scrape the Web.
Presidents Data:

Use stringr package: Here we used str split() to split a column based on a
pattern.

Use Reduce() to combine the rows into a Matrix.

Final Results.

Summary
Packages and Functions
Data Packages Functions
CSV Base read.csv(),read.csv2(), read.table()
Excel XLConnect readWorksheetFromFile()
Database RODBC odbcConnect()
SAS sas7bdat read.sas7bdat()
All other foreign read.spss(), read.dta(), read.octave()
read.mtp(),read.sysstat()
Table : R Packages for reading Structured Data

Summary
Use ﬁles across platforms- Windows,Mac,and Linux OS.
Use Rdata ﬁles to pass around data or any R objects like variables and
functions.
Use Save().

Summary
References
Jared P. Lander (2013)
R for Everyone: Advanced Analytics and Graphics
Addison-Wesley Data & Analytics Series.

Reading data into r

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