INTRODUCTION TO RNimrod Priell, October 2012

Thursday, September 5, 13

WHAT IS R?

Thursday, September 5, 13

WHAT IS R?

What is C?

General-purpose programming language

How do you pick all pairs of researchers and managers in C?

Thursday, September 5, 13

WHAT IS R?

What is C?

General-purpose programming language

How do you pick all pairs of researchers and managers in C?

          char** researchers ... /* Lior, Nimrod, Gadi */          char** managers ... /* Eran, Gadi, Roi */          int i = 0          int j = 0          for (int i = 0; i < 3; i++) {               for (int j = 0; j < 3; j++) {                    if (strncmp(researchers[i], researchers[j], 30)) {                         ... // expand our list, blah blah headache

Thursday, September 5, 13

WHAT IS R?

What is Python?

General purpose scripting language

How do you pick all pairs of researchers and managers in Python?

Thursday, September 5, 13

WHAT IS R?

What is Python?

General purpose scripting language

How do you pick all pairs of researchers and managers in Python?

[ (x, y) for x in [‘Gadi’,‘Nimrod’,‘Lior’] for y in [‘Gadi’, ‘Roi’, ‘Eran’] if x != y ]

Thursday, September 5, 13

WHAT IS R?

What is Python?

General purpose scripting language

How do you multiply matrices in Python?

Thursday, September 5, 13

WHAT IS R?

What is Python?

General purpose scripting language

How do you multiply matrices in Python?

def  matrixmult  (A,  B):        C  =  [[0  for  row  in  range(len(A))]  for  col  in  range(len(B[0]))]        for  i  in  range(len(A)):                for  j  in  range(len(B[0])):                        for  k  in  range(len(B)):                                C[i][j]  +=  A[i][k]*B[k][j]        return  C

Thursday, September 5, 13

WHAT IS R?

What is Python?

General purpose scripting language

How do you multiply matrices in Python?import  numpy  as  npx  =  np.arange(9).reshape((3,3))y  =  np.arange(3)print  np.dot(x,y)x.T.dot(A.T).dot(A.inverse()).dot(x)

Thursday, September 5, 13

WHAT IS R?

What is Matlab?

Algebraic programming language

How do you multiply matrices in Matlab?

A = [ 1 2 3;        4 5 6;        7 8 9 ]b = [ 6 4 -1 ]A’ * b’ * b / A

Thursday, September 5, 13

WHAT IS R?

Incidentally, what is APL? (“A Programming Language”)

 life←{↑1 ⍵∨.∧3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵} (Conway's game of life in APL)

Thursday, September 5, 13

WHAT IS R?

Statistical programming language

Interpreted, Object Oriented, Functional

First-class data-sets, plotting and models.

cov(data$Income[data$Gender == ‘M’ & data$country %in% c(‘uk’,’us’,’il’)], data$LifeExp[data$Gender == ‘F’ & data$Age > 14])

lm(data, Income ~ Gender + Age)

predict(model, data)

Thursday, September 5, 13

WHY R?

Alternatives: Stata, SPSS, SAS, Excel

R is Free and Open Source

Packages for time-series, machinelearning, biological simulation,computer vision, GPS, MapReduce,animation, optimization, graphanalysis, reading any kind of dataformat, weather prediction, ...

academia contributing packages

http://cran.r-project.org/web/packages/

Thursday, September 5, 13

WHY R?

R has Reproducible Research

Excel: Click death

Demo #1

Thursday, September 5, 13

WHY R?

R is a general purpose programming language

Thursday, September 5, 13

WHY R?

R is a general purpose programming language

Thursday, September 5, 13

WHY R?

R is a general purpose programming language

Thursday, September 5, 13

WHY R?

R is a general purpose programming language

Other alternatives are very specific: Weka, Orange, etc.

Thursday, September 5, 13

R DEMO

The DataFrame

IO

Statistics & Models

Plotting

Remote RStudio

https://gist.github.com/2838511

Thursday, September 5, 13

WHY NOT R?

Terribly slow...

... But there’s RCPP, RHadoop and multicore

Terrible OO support and very quirky language

... But that only bothers you if you write packages

Thursday, September 5, 13