AnintroductiontoRJorgeCimentadaandBasilioMoreno

6thofJuly2019

RstudioisjustanicesoftwaretorunR!

Afactorisjustawayofsayingthatavariablehas

uniquevalues!Andtheycanbeordered.

elm<-c("Good","Bad","Medium")(elm_factor<-factor(elm,levels=c("Bad","Medium","Good"),ordered=T))

[1]GoodBadMediumLevels:Bad<Medium<Good

Thishasconsequencestable(elm)

elmBadGoodMedium111

table(elm_factor)

elm_factorBadMediumGood111

HowtoinstallR?Luckily,youguyshaveRandRstudioinstalled,soyou

don'thavetoworryaboutthis!

Butifyouwanttoinstallitathome,pleasefollow

ThatguidecanhelpyouinstallRRstudioAndswirl,apackageinwhichyoucoulddoabunchofexercisesashomework!

thisguide

WhatisR?Risaprogramminglanguagedesignedtododata

analysis,usuallyinteractive.

Rishelpfulfor..Gettingthatdarnexcel/statafileintoR(importing)Turningthatveryuglydatasetintosomethingtoworkwith(datacleaning)Automatingyourweeklyreports(automatingtasks)Analyzingdata(modeling)Creatingnicelyformatteddocuments(communicatingresults)Buildingyourowncommandstodospecificthings(functions)

Buildingverycreativegraphics

Amongmanythings…

Andso..whatisRstudio?

Andso..whatisRstudio?

Let'sgettoitthen!Risaninteractivelanguage.Thatmeansthatifyoutype

anumber,youwillgetanumber.#Input10

[1]10

#Input5

[1]5

IntroductiontoRobjectsRisalsoacalculator

TrytypingtheseoperationsinR:5+510-510*520/10(10*20)-5/2+22^3

Beforewecontinue,whattypeofoperationsarethese?

Answersinnextslide!

IntroductiontoRobjectsAdditionSubtractionMultiplicationDivisionAcombinationofallExponentiation

NumbersinRarecallednumerics.

Forexample:is.numeric(10)is.numeric(10+20)is.numeric(10/2)

IntroductiontoRobjectsHavingsinglenumbers,like10,isnotveryuseful.

Wewantsomethingsimilartoacolumnofadataset,likeageorincome.

Wecandothatwithc(),whichstandsforconcatenate.

Readthisexpressionas:concatenatethesenumbersintoasingleobject.

c(32,34,18,22,65)

[1]3234182265

IntroductiontoRobjectsWecanalsogiveitaname,likeage.

Whydidn'ttheresultgetprinted?Whereisthisageobjectat?Whatisformallytheageobject?

age<-c(32,34,18,22,65)

IntroductiontoRobjectsWejustcreatedourfirstvariable!Thetypical

SAS/Excel/Statacolumn.

InR,theseobjectsarecalled'vectors'.

Vectorscanhaveseveralflavours:Numerics(wejustsawone)LogicalsCharactersFactors

IntroductiontoRobjectsSupposetheseagesbelongtocertainpeople.Wecan

createacharactervectorwiththeirnames.

Followingthisguideline,createityourself.Createacharactervectorwithc()IncludethenamesPaul,Maria,Andres,RobertoandAliciainsidewrapeverynameinquoteslikethis“Paul”,“Maria”,etc…ThiswillmakeRunderstandthatinputascharacters.

IntroductiontoRobjectsAnswer:

Wecanalsogiveitaname,likeparticipants.

c("Paul","Maria","Andres","Robert","Alicia")

[1]"Paul""Maria""Andres""Robert""Alicia"

participants<-c("Paul","Maria","Andres","Robert","Alicia")

IntroductiontoRobjectsCharactervectorsarefilledbystrings,like“Paul”or

“Maria”.

Canwedooperationswithstrings?

Makessense..wecan'taddanyletters.

Alright,we'reset.Concatenatethenumericvectorageandparticipants.

"Paul"+"Maria"

Errorin"Paul"+"Maria":non-numericargumenttobinaryoperator

IntroductiontoRobjects

What'stheproblemwiththisresult?

c(age,participants)

[1]"32""34""18""22""65""Paul""Maria"[8]"Andres""Robert""Alicia"

ThisbreaksanRlaw!Wejoinedanumericvectorandacharactervector.

VectorscanONLYbeofoneclass.c(1,"one")#forcestocharactervector

[1]"1""one"

c(1,"1")#notethatthefirstoneisanumeric,whilethesecondisacharacter

[1]"1""1"

IntroductiontoRobjectsNow,whichofthesepeoplehasanageabove20?

That'salogicalvector.

Contrarytocharacterandnumericvectors,logicalvectorscanonlyhavethreevalues:

TRUEFALSENA(whichstandsfor“Notavailable”.)

age>20

[1]TRUETRUEFALSETRUETRUE

IntroductiontoRobjectslogicalscanbecreatedmanuallyorwithalogical

statement.

Theaboveexpressiontestsforthelogicalstatement.

Forexample,

c(TRUE,FALSE,TRUE,TRUE)

[1]TRUEFALSETRUETRUE

age<60

[1]TRUETRUETRUETRUEFALSE

3234182265TRUETRUETRUETRUEFALSE

IntroductiontoRobjectsYoucanalsowriteTorFasshortabbreviationsofTRUE

andFALSE.

Whichiscomparing:

Butbehindthescenes,TRUEandTarejusta1andFandFALSEarejusta0.

Whatistheresultofthis?

c(T,T,F,T)==c(TRUE,TRUE,FALSE,TRUE)

[1]TRUETRUETRUETRUE

TRUETRUEFALSETRUE"T""T""F""T"

T+5TRUE-5FALSE+TRUET+T-FALSE

IntroductiontoRobjectsNowthatyouknowthat..whatwouldbetheclassofthe

followingvectors?

numeric:TRUEiscoercedto1character:“FALSE”isastring,can'tbeturnedtoanumberlogical:bothelementsarelogical!numeric:FALSEiscoercedto0

c(5,TRUE)c(5,"FALSE")c(FALSE,TRUE)c(1,FALSE)

IntroductiontoRobjectsWhatdoweknowsofar?

NumericvectorsCharactervectorsLogicalvectorsHowtoassignanametothesevectorsVectorscancontainonlyoneclassofdata

What'smissing?Factors

IntroductiontoRobjectsFactorsareR'swayofstoringcategoricalvariables.

Categoriessuchas:'Male'and'Female'or'Married'and'Divorced''Good','Middle'and'High'

gender<-c("Male","Female","Male","Male","Female")

#Canbeturnedinto

gender<-factor(gender)

IntroductiontoRobjects

IntroductiontoRobjectsFactorsareusefulforsomespecificoperationslike:

ChangingorderoflevelsfortermsinmodellingChangingorderofaxislabelsinplotsAmongotherthings..

Inmanycasesyoucanusecharacterstodowhatyouwouldwantwithfactors!

IntroductiontoRobjectsNow,haveyounoticedthatwe'vebeenassigningnames

tothings?

Thenameageholdsalltheseelementsinside.Howdoweknowwhereallthevariableswe'vecreatedare?

Let'saskRwhatobjectscanbelistedfromourworkspaceorenvironment.

age

[1]3234182265

ls()

[1]"age""elm""elm_factor""gender"[5]"lgl""participants"

IntroductiontoRobjectsSofar,wehaveabunchofvariablesscatteredaround

ourworkspace.Thisisusuallynothewaytogo!Wewanttogroupsimilarthingsinthesameplace.

AdataframeisusuallytheprimarystructureofanalysisinR

our_df<-data.frame(name=participants,age=age,gender=gender,age_60=lgl)our_df

nameagegenderage_601Paul32MaleTRUE2Maria34FemaleTRUE3Andres18MaleTRUE4Robert22MaleTRUE5Alicia65FemaleFALSE

IntroductiontoRobjectsIt'simportantthatyouunderstandthethingthatdefines

adataframe.Adataframehasrowsandcolumns,moretechnicallycalleddimensions.Dataframeshavetwodimensions.

dim(our_df)

[1]54

nrow(our_df)

[1]5

ncol(our_df)

[1]4

IntroductiontoRobjectsDataframesareverydistinctivebecausetheycanhold

anytypeofvector.

Matricescannot!

Matricesareverysimilartodataframes.Theyhavesamenumberofdimensions.Youcanchooserows/columnsinsimilarways.

our_matrix<-matrix(1:20,ncol=4,nrow=5)our_matrix

[,1][,2][,3][,4][1,]161116[2,]271217[3,]381318[4,]491419[5,]5101520

IntroductiontoRobjectsFinally,we'remissingthesecretingridientthedifferentiatesbothmatricesanddataframes.

Lists

IntroductiontoRobjectsThinkoflistsasabagthatcanstoreanything.

Thisisabagthathas3objects.AcharachterAfactorAnumeric

our_list<-list(names=participants,gender=gender,age=age)our_list

$names[1]"Paul""Maria""Andres""Robert""Alicia"

$gender[1]MaleFemaleMaleMaleFemaleLevels:FemaleMale

$age[1]3234182265

IntroductiontoRobjectsThinkoutsidethebox…whenIsayanything,Imean

ANYTHING!complex_list<-list(df=our_df[1:3,],matrix=our_df[1:3,],avg_age=mean(age))complex_list

$dfnameagegenderage_601Paul32MaleTRUE2Maria34FemaleTRUE3Andres18MaleTRUE

$matrixnameagegenderage_601Paul32MaleTRUE2Maria34FemaleTRUE3Andres18MaleTRUE

$avg_age[1]34.2

IntroductiontoRobjectsTosumup,thesearethe4typesofdatastructures

availableinR.

IntroductiontoRobjectsNowI'mgonnarockyourworld…

Adataframeisalist(becauseitcanhaveanyclass)witharowandcolumndimensions.

data.frame(our_list)

namesgenderage1PaulMale322MariaFemale343AndresMale184RobertMale225AliciaFemale65

Tobecontinued….