MATLAB R Dictionary

8/6/2019 MATLAB R Dictionary

http://slidepdf.com/reader/full/matlab-r-dictionary 1/17

MATLAB/RDic,onary

RmeetupNYCJanuary72010

HarlanHarris

[email protected]

@HarlanH

MarckVaisman

[email protected]

@wahalulu

MATLABandtheMATLABlogoareregisteredtrademarksofTheMathworks.



AboutMATLAB

WhatisMATLAB

• Commercialnumerical

programminglanguage

simula,onandvisualiza,on• Onemillionusers(engineers

scien,stsacademics)

• MATrixLABoratory–

specializesinmatrix

opera,ons

• Mathworks-base&add-ons

• Open-sourceOctaveproject

MATLABHistory

• DevelopedbyCleveMoler

(Math/CSProfatUNM)inthe

1970’sasahigher-levelnumericalprogramming

language(vs.FortranLINPACK)

• Adoptedbyengineersfor

signalprocessingcontrol

modeling• Mul,purposeprogramming

language



Notes

• Today’sfocus:CompareMATLAB&Rfordata

analysiscontrastasprogramminglanguages

• MATLABisBaseplusmanytoolboxes

– Baseincludes:descrip,vestatscovarianceand

correla,onlinearandnonlinearregression

– Sta,s,cstoolboxadds:datasetandcategory(like

data.framesandfactors)arraysmorevisualiza,ons

distribu,onsANOVAmul,variateregressionhypothesistests



->

• Interac,veprogramming:ScriptsandRead-Evaluate-

PrintLoop

• Similarrepresenta,onsofdata

– Bothusevectors/arraysastheprimarydatastructures• Matlabisbasedon2-Dmatricies;Risbasedon1-Dvectors

– Bothprefervectorizedfunc,onsto for loops

– Variablesaredeclareddynamically

• CandomostMATLABfunc,onalityinR;candomost

Rfunc,onalityinMATLAB.



Thebasics:vectorsmatricesandindexing

Task

Createarowvector v=[1234] v<-c(1,2,3,4)

Createacolumnvector v=[1;2;3;4]orv=[1234]’ v<-c(1,2,3,4)Note:Rdoesnotdistinguish

betweenrowandcolumnvectors

EnteramatrixA A=[123;456] Entervaluesbyrow:

A<-matrix(c(1,2,3,4,5,6),

nrow=2,byrow=TRUE)Entervaluesbycolumn:

A<-matrix(c(1,4,2,5,3,6),nrow=2)

Accessthirdelementofvectorv v(3) v[3]orv[[3]]

AccesselementofmatrixA A(2,3) A[2,3]

“Glue”twomatricesa1anda2

samenumberofrowssidebyside

A=[a1a2] A<-cbind(a1,a2)

“Stack”twomatricesa1anda2

samenumberofcolumns

A=[a1;a2] A<-rbind(a1,a2)

Reshape*matrixAmakingitanm

xnmatrixwithelementstaken

columnwisefromA

A=reshape(A,m,n) dim(A)<-c(m,n)



Operators

Task

Assignment = <-or=

WholeMatrixOpera,ons: Multiplication:A*BSquarethematrix:A^2Raisetopowerk:A^k

A%*%BA%*%AA%*%A%*%A…

Element-by-element

Opera,ons:

A.*BA./B

A.^k

A*BA/B

A^k

ComputeA-1B A\B A%*%solve(B)

Sums Columnsofmatrix:sum(A)Rowsofmatrix:sum(A,2)

colSums(A)rowSums(A)

Logicaloperators(element-by-

elementonvectors/matrices)

a<b,a>b,a<=b,a>=ba==b

a~=bAND:a&&b

OR:a||b

XOR:xor(a,b)NOT:~a

a<b,a>b,a<=b,a>=ba==b

a!=bAND:a&&b(short-circuit)a&b(element-wise)OR:a||ba|b

XOR:xor(a,b)NOT:!a



Workingwithdatastructures

Task

Buildastructurevoflengthn

capableofcontainingdifferent

datatypesindifferentelements.

MATLAB:cellarray

R:list

v=cell(1,n)Ingeneral,cell(m,n)makesanm×ncell

array.Thenyoucandoe.g.:v{1}=12

v{2}=’hithere’

v{3}=rand(3)

v<-vector(’list’,n)Thenyoucandoe.g.:

v[[1]]<-12v[[2]]<-’hithere’

v[[3]]<-matrix(runif(9),3)

Createamatrix-likeobjectwith

differentnamedcolumns.

MATLAB:structarray

R:data.frame

avals=2*ones(1,6);yvals=6:-1:1;v=[153237];

d=struct(’a’,avals,’yy’,yyvals,’fac’,v);

v<-c(1,5,3,2,3,7)d<-data.frame(cbind(a=2,

yy=6:1),v)



Condi,onalscontrolstructuresloops

Task

or loopsovervaluesinvector

v

fori=vcommand1

command2end

Ifonlyonecommand:for(iinv)

command

Ifmultiplecommands:

for(iinv){command1command2

}

If/elsestatement ifcondcommand1command2

elsecommand3command4

end

MATLABalsohastheelseif

statement.

if(cond){command1command2

}else{command3command4

}

Ruseschained“elseif”

statements.

ifelse()func,on >print(ifelse(c(T,F),2,3))[1]23



Help!

Task

Gethelponafunc,on helpfminsearch help(pmin)or

?pmin

Searchthehelpforaword lookforinverse ??inverse

Describeavariable class(a) class(a)str(a)

Showvariablesinenvironment who ls()

Underlyingtypeofvariable whos(‘a’) typeof(a)



Example:k-meansclusteringofFisherIrisdataFisherIrisDataset

sepal_length,sepal_width,petal_length,petal_width,species5.1,3.5,1.4,0.2,setosa4.9,3.0,1.4,0.2,setosa

4.7,3.2,1.3,0.2,setosa4.6,3.1,1.5,0.2,setosa…



MatlabandRasprogramminglanguages

Scrip,ngreal-,meanalysis Scrip,ngreal-,meanalysis

File-basedenvironments Filesunimportant

Impera,veprogrammingstyle Func,onalprogrammingstyle(impure)

Sta,callyscoped Dynamicallyscoped

Func,onswithmul,plereturnvalues Func,onswithnamedargumentslazy

evalua,on

EvolvingOOPsystem Mul,plecompe,ngOOPsystems

Canbecompiled Cannotbecompiled

Largelibraryoffunc,ons

Professionaldevelopedcostmoney

Largelibraryoffunc,ons

Varyingqualityandsupport

Canembed(in)manyotherlanguages Canembed(in)manyotherlanguages



Func,ons

function[a,b]=minmax(z)%onefunctionper.mfile!%assigntoformalreturnnamesa=min(z)b=max(z)

end

%ifminmax.minpath[smallest,largest]=…

minmax([1303])

minmax<-function(c,opt=12){#functionsareassignedto#variablesret<-list(min=min(z),max=max(z))

ret#laststatementis#returnvalue}

#ifminmaxwascreatedincurrent#environmentx<-minmax(c(1,30,3))

smallest<-x$min



Othernotes

• r.matlabpackage

• Graphics

– Matlabhasmuchbeer3-d/interac,vegraphicssupport

– Rhasggplot2andmuchbeersta,s,calgraphics



Addi,onalResources

• WillDwinellDataMininginMATLAB

• Computerworldar,cleonCleveMoler

• Mathworks

• Matlabcentral

• ComparisonofDataAnalysispackages(hp://anyall.org/blog/2009/02/comparison-of-data-analysis-packages-r-matlab-scipy-excel-sas-spss-

stata/)• R.matlabpackage

• stackoverflow



Referencesusedforthistalk

• DavidHiebelerMATLAB/RReferencedocument:

hp://www.math.umaine.edu/~hiebeler/comp/

matlabR.html

• hp://www.cyclismo.org/tutorial/R/index.html

• hp://www.stat.berkeley.edu/~spector/R.pdf

• MATLABdocumenta,on

• hp://www.r-cookbook.com/node/23



ThankYou!

MATLAB R Dictionary

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