1. 1
What is R?
Official website: http://www.cran.r-project.org
1. R is free, open-source statistical analysis software. Its a
competitor to many commercial software packages such as
MathLab, Microsoft Excel, SPSS, etc.
2. R is open source and has a very active user groups and
contributors
3. R architecture Basic functionality + additional
packages(optional)
4. Basic functionality comes with installation
5. Additional packages are imported as needed and loaded
before they can be used
6. R has a Good online help!
2. 2
Example of Utility of R : Statistical Data Analysis & Data Visualization
Exploratory data analysis
When analyzing data in sciences (Data mining, Machine learning, Social
Science, etc.) , most researchers use Ms Excel, MathLab, SPSS, etc. to
store, edit, and analyze their data. For example, if researcher is studying
students appraisal of a courses, he may have participants complete an
online survey. The researcher might combine individual answers to create a
global course score. Then, the next step would be to perform a statistical
test to look for group differences among students on a particular course, or
calculate correlations with other items of interest (Mean, median,
correlation, standard deviation, etc.).
Data visualization
In many cases one would like to visualize the dataset
R provides a great way to achieve the above objectives.
3. 3
Basic structure of R
Add-on Packages
(Import)
Basic
Packages
(Installation)
Basic packages are available after installation.
Usually located at C:/Program Files/R/R-2.15.1/library
This location could be different depending on your particular installation
Additional libraries are imported as needed
R
4. 4
Illustrating Few Key Features of R
1-Scatterplot
s3d <-scatterplot3d(SepalWidth,PetalLength,SepalLength, pch=16, highlight.3d=TRUE, type="h", main="3D
Iris Scatterplot")
fit <- lm(SepalLength ~ SepalWidth+PetalLength)
s3d$plane3d(fit)
3D Iris Scatterplot
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9. 9
Installation
1. Go to http://cran.r-project.org/mirrors.html.
The R installations are distributed by the Comprehensive R Archive Network (CRAN). CRAN is a
collection of sites which carry identical materials and were created as mirror sites to lessen the load on any one
server.
2. Click on one of the USA links, select for example http://lib.stat.cmu.edu/R/CRAN/, which brings you to
Carnegie Mellon University's Statlib mirror site. (Select a site close to where you are)
3. In the Download and Install R box, click on the `Windows' link.
4. Click on the `base' link.
5. Right-click on the `Download R 2.9.1 for Windows' link and choose `Save Link As. . . '.
6. Save the .exe _le to your Desktop (the R-2.9.1-win32.exe _le is R-3.0.1-win.exe approximately 36Mb 52 Mb).
7. Double-click on the .exe icon and follow the instructions.
8. When asked to `Select the components you want to install', choose the (default) `User' installation.
Don't worry about `customizing the startup options'.
In general, you should install R perfectly by just clicking on the `Okay', `Next', or `Finish' buttons at each step and
letting the R set-up use the default choices.
11. 11
Preliminaries
R is case sensitive
# is the comment tag
R is installed with a default library/packages. You
add/ import additional Packages to the library using
the command library()
To use a library function you must load it first into
memory using the command load()
Basic instructions are memory resident (you do not
need to load them)
Variable names cannot start with . (dot), + (plus
sign) or -(minus sign)
12. 12
Preliminaries
No variable declaration is needed. Variables are called objects and are memory
residents.
Assignment is achieved with the command assign()
For example: assign("x", c(10.4, 5.6, 3.1, 6.4, 21.7)) put the vector into x
Symbol for assignment : <- ( this is a shortcut)
To Print on screen just type the variable name followed by ENTER or use cat(),
or print()
Example
A<-2
cat(A) will display 2 on the screen
Command are separated by ; or by new line character
Use the setwd command to set a working directory
For example : setwd("C:/Documents and Settings/username/My
Documents/xyz/")
13. 13
Few Basic Commands
help(topic) or help(help=topic) or ?topic
In the command line if you type help(topic) R
will fetch information about the topic you need
help with. A topic is either an instruction or a
package name
For example, help() or help(help) will provide
help about the help instruction
example(topic) # will provide examples of
how to use the instruction (topic)
14. 14
q() to quit R.
source(path) to execute several lines of
instructions stored in a file (sometime better
than interactive mode).
Path: where is the path to the file.
File containing R script have the extension .r
For example
Source (source1.r) will execute everything in the
file assuming source1.r is in the working directory
15. 15
source() is also available under the menu.
(window)
File>> Source R Code then select the file
sink( outputFile) command will redirect all
output to the outputFile. For example
sink("record.lis") will output to record.lis
sink() will restore the output back to the
console. (no argument provided)
16. 16
Data permanency and removing objects
l() :To print the workspace on the console
workspace :list of most objects currently in
memory
rm: (object names separated by commas) to
remove one or more objects from the
workspace
You may use the File menu to save or load
workspaces
17. 17
Non interactive mode: R-editor
You may use the R-editor to edit a script then
run/save. (File >> New Script)
18. 18
RCommander
RCommander is an external R-
editor package that needs to be
imported
Packages>> load packages
scroll until you find Rcmdr
Non interactive mode: RCommander
![7
#Demonstrating k-mean clustering
library(cluster)
library(fpc)
dataset =
read.csv("C:/Users/paul/Desktop/R_wd/Lab/i
ris.csv")
mysubSet<- dataset[1:4]
obj<-kmeans(mysubSet,centers=3)
#plot result
plot(mysubSet,obj$cluster,pch=obj$cluster)
plotcluster(mysubSet,obj$cluster)
#Clustering quality result
obj$centers
obj$totss
obj$withinss
obj$size
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2-Object manipulation/clustering analysis](https://image.slidesharecdn.com/rpreliminaries-240804071405-66fcb60e/85/RPreliminariesdsjhfsdsfhjshfjsdhjfhjfhdfjhf-7-320.jpg)
