1 The R Project for statistical computing Eric Fouh, Christopher Poirel CS 5604 Fall 2010.

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The R Project for statistical computing

Eric Fouh, Christopher Poirel

CS 5604

Fall 2010

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What is R?

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Usages of R

• statistics system

• data handling and storage facility

• calculations on arrays, in particular matrices

• integrated collection of tools for data analysis

• graphical tool for data analysis

• programming language (called ‘S’)

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Structure of R• R functions and dataset are stored in packages

• R is provided with 25 “standard” packages:

• Hundreds of contributed packages (written by different authors ) are available

Package Name Description

baseBase R functions

dataset Base R datasets

graphicsR functions for base graphics

stats R statistical functions

utils R utility functions

matrix Matrix package

class Functions for classification

clusterFunctions for cluster analysis

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R and Information Retrieval

IR Concept R package

Text preprocessing

Term weighting, scoring

tm package: Constructs a term-document matrix, using one of the the following weighting functions TF (weightTf), TF-IDF

(weightTfIdf). e.g. tdm <- TermDocumentMatrix(crude, control = list(weighting = weightTfIdf, stopwords = TRUE))

vector space model for scoring clv package: dot.product function returns a cosine similarity

measure of two vectors.

vector space classification class package: performs a k-Nearest Neighbour Classification on a dataset

Hierarchical clustering Cluster package: computes clusters (agglomerative hierarchical ) on dataset

Latent Semantic Indexing Base package: performs Singular Value Decomposition on matrix

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Getting started with R• To start R

>R• To quit R

>q()• To see installed packages

>library()• To load a package

>library(class)• To start help

> help.start()• To create a vector

> x <- c(10.4, 5.6, 3.1, 6.4, 21.7)• To create a matrix

> x <- array(1:20, dim=c(4,5)) # Generate a 4 by 5 array filled with number from 1 to 20.• To display an object

>x• To delete an object

>rm x• To load data from file

>HousePrice <- read.table("houses.data")

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Examples (1)

• Term-Document Matrix

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Examples (1)

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Examples (2)

• Eigenvalues and eigenvectors

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Examples(3)

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Examples(3)

• Law Rank approximation

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Examples(3)

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Examples(3)

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Resources

• IIR Book

• http://www.r-project.org/

Questions?