MATLAB/R Dictionary R meetup NYC January 7, 2010 - PowerPoint PPT Presentation

MATLAB/R DictionaryR meetup NYCJanuary 7, 2010

Harlan Harris

harlan@harris.name

@HarlanH

Marck Vaisman

marck@vaisman.us

@wahalulu

MATLAB and the MATLAB logo are registered trademarks of The Mathworks.

What is MATLAB

MATLAB History

Developed by Cleve Moler (Math/CS Prof at UNM) in the 1970’s as a higher-level numerical programming language (vs. Fortran LINPACK)

Adopted by engineers for signal processing, control modeling

Multipurpose programming language

• Commercial numerical programming language, simulation and visualization
• One million users (engineers, scientists, academics)
• MATrixLABoratory – specializes in matrix operations
• Mathworks - base & add-ons
• Open-source Octave project

• Today’s focus: Compare MATLAB & R for data analysis, contrast as programming languages
• MATLAB is Base plus many toolboxes
• Base includes: descriptive stats, covariance and correlation, linear and nonlinear regression
• Statistics toolbox adds: dataset and category (like data.frames and factors) arrays, more visualizations, distributions, ANOVA, multivariate regression, hypothesis tests

• Interactive programming: Scripts and Read-Evaluate-Print Loop
• Similar representations of data
• Both use vectors/arrays as the primary data structures
• Matlab is based on 2-D matricies; R is based on 1-D vectors
• Both prefer vectorized functions to for loops
• Variables are declared dynamically
• Can do most MATLAB functionality in R; can do most R functionality in MATLAB.

Fisher Iris Dataset

sepal_length,sepal_width,petal_length,petal_width,species

5.1,3.5,1.4,0.2,setosa

4.9,3.0,1.4,0.2,setosa

4.7,3.2,1.3,0.2,setosa

4.6,3.1,1.5,0.2,setosa

…

minmax <- function(c, opt=12) {

# functions are assigned to

# variables

ret <- list(min = min(z),

max = max(z))

ret # last statement is

# return value

}

# if minmax was created in current

# environment

x <- minmax(c(1, 30, 3))

smallest <- x$min

function [a, b] = minmax(z)

% one function per .m file!

% assign to formal return names

a = min(z)

b = max(z)

end

% if minmax.m in path

[smallest, largest] = …

minmax([1 30 3])

• Formerly: objects were defined by a directory tree, with one method per file
• As of 2008: new classdef syntax resembles other languages

• S3 classes: attributes + syntax
• class(object)
• plot.lm()
• S4 classes: definitions + methods
• R.oo, proto, etc…

• r.matlab package
• Graphics
• Matlab has much better 3-d/interactive graphics support
• R has ggplot2 and much better statistical graphics

• Will Dwinell, Data Mining in MATLAB
• Computerworld article on Cleve Moler
• Mathworks
• Matlabcentral
• Comparison of Data Analysis packages (http://anyall.org/blog/2009/02/comparison-of-data-analysis-packages-r-matlab-scipy-excel-sas-spss-stata/)
• R.matlab package
• stackoverflow

• David Hiebeler MATLAB/R Reference document: http://www.math.umaine.edu/~hiebeler/comp/matlabR.html
• http://www.cyclismo.org/tutorial/R/index.html
• http://www.stat.berkeley.edu/~spector/R.pdf
• MATLAB documentation
• http://www.r-cookbook.com/node/23