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Part IVMaking the Data TalkIn this part . . .R has earned its status as one of the leading statistical packages for a reason.Statisticians use it to extract meaningful relationships from sometimes gigabytes ofavailable data in a variety of ways. For them, R is often the right tool to convert abunch of numbers into an interesting story.In this part, you meet a small selection of tools that allow you to tell the storyof your data. You get to subset, combine, and restructure your data; summarize itin meaningful ways; and use the power of statistics to test your hypotheses on thedata at hand.Because thousands of people continue to develop new statistical techniquesand write new R packages, this section covers only a tiny spectrum of possibleanalyses. But you do get insight into how you formulate tests and what you can dowith the resulting objects.
Chapter 12Getting Data into and out of RIn This ChapterExploring the various ways of getting data into RLooking at how to save your resultsUnderstanding how files are organized in REvery data-processing or analysis problem involves at least three broad steps:input, process, and output. In this chapter, we cover the input and output steps.In this chapter, we look at some of the options you have for importing yourdata into R, including using the Clipboard, reading data from comma-separatedvalue (CSV) files, and interfacing with spreadsheets like Excel. We also give yousome pointers on importing data from commercial software such as SPSS. Next, wegive you some options for exporting your data from R. Finally, you get tomanipulate files and folders on your computer.Getting Data into RYou have several options for importing your data into R, and we cover thoseoptions in this section.Because spreadsheets are so widely used, the bulk of this chapter looks at thedifferent options for importing data originating in spreadsheets. To illustrate thetechniques in this chapter, we use a small spreadsheet table with informationabout the first ten elements of the periodic table, as shown in Figure 12-1.Entering data in the R text editorAlthough R is primarily a programming language, R has a very basic dataeditor that allows you to enter data directly using the edit() function.Figure 12-1: A spreadsheet with elements of the periodic table serves as our example
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Running code without a compilerChap
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Creating errorsCreating warningsRec
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Analyzing tablesExtracting test res
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Working with Pivot TablesUsing the
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R For Dummies ®Published byJohn Wi
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About the AuthorsAndrie de Vries: A
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my choices. Professor Bruce Hardie
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IntroductionWelcome to R For Dummie
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: The prompt symbol, >, is not part
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You want to explore new stuff. You
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Icons Used in This BookAs you read
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Chapter 1Introducing R: The Big Pic
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eferred to as “free as in beer.
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you how to move data and graphics b
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If you have experience in other lan
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variables, get to look at the built
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Below all this information is the R
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that we use it to illustrate the ex
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Starting Your First R SessionIf you
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Using R as a calculator is very int
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Sourcing a ScriptUntil now, you’v
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Finding help on functionsWe discuss
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languages, the backslash character
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Vectorizing your functionsVectorize
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print()R tells you that it needs th
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extensions that much. But using .Rh
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Choosing a clear nameWhen Joris was
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opinions, so the naming of function
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Often, you want to add a bit of ext
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all of them at the beginning of eac
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Part IIGetting Down to Work in RIn
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calculator.Vector operations: Vecto
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Suppose that Granny and Geraldine d
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FunctionWhat It Doesabs(x)log(x,bas
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decision to use scientific notation
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operations in Chapter 7.Actually, o
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NaN in calculations. The outcome of
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Take a look at the vector baskets.o
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way the value is stored in memory.R
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[1] 12 4 4 6 9 3 5 3 2 2 12 9The re
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Okay, this example isn’t too impr
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R doesn’t have an Undo button, so
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x < yx baskets.of.Granny > 5[1] TR
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that value (refer to “Dealing wit
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all(). To find out whether Granny w
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You can tell quite a few things abo
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third game, and so on.The vector re
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1st 2nd 3rd 4th 5th 6th-67 25 20 50
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In this section, you take a look at
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LETTERS[24:26][1] “X” “Y”
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Creating and assigning named vector
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Similar to the way that R displays
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[1] “The quick brown FOX jumps ov
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R performs lexicographic sorting, a
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The result of grep() is a numeric v
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Suppose you have the sentence He is
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Regular expressions allow three way
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lexicographically sorted, unique va
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difference between the levels and t
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vector subsisting rules. For exampl
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table(state.region)state.regionNort
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Chapter 6Going on a Date with RIn T
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startDate xm xm[1] “2012-01-01
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Table 6-2 Some Format Codes for Dat
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As you can see, as.POSIXct() takes
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Formatting Dates and TimesTo format
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Now you know the exact time when we
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project.org/web/packages/lubridate/
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They contain only a single type of
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To get only the number of rows, you
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[1,] 1 4 7 10[2,] 2 5 8 11[3,] 3 6
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id first.matrix[-id][1] 1 2 3 4 5
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[2,] 2 5 8 11[3,] 3 4 9 12You also
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the way. You can try that out yours
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constructing a matrix second.matrix
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[2,] 4 5 6[3,] 7 8 9[4,] 10 11 12Yo
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Using the creator functionsYou can
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[2,] 5 17[3,] 8 20[4,] 11 23This re
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[1] 6Likewise, the ncol() function
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data frame with character vectors o
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section, earlier in this chapter.Ex
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As explained in the “Combining ve
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Create a matrix with two columns.Cr
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Although the row names of the data
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you, because data frames are, in fa
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You can’t use logical vectors or
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askets.nlist baskets.nlist[‘scor
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The second line contains a $, which
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Part IIICoding in RIn this part . .
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Making the scriptSuppose you want t
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There’s no way you can define in
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Luckily, this problem doesn’t occ
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addPercent
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addPercent(new.numbers)Error in x *
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list instead of using the dots.So,
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code. So, instead of giving a funct
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Instead of passing the code of the
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Using internal functionsWriting you
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weird, think again about data frame
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print.default(small.one)$a[1] 1 2$b
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can easily add a default method exa
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Page 231 and 232: Chapter 10Debugging Your CodeIn Thi
Page 233 and 234: R always tells you in which code th
Page 235 and 236: If you get warning or error message
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Page 251 and 252: From the description of ada::update
Page 253 and 254: Getting Involved in the R Community
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Page 265 and 266: Using special characters in escape
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Page 271 and 272: These functions need a specific fil
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Page 277 and 278: can confirm this by taking a close
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+ y ~ a + b Include columns a as we
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In the world of R, people usually r
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Now you can start. First, create so
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data: A molten data frame.formula:
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Chapter 14Summarizing DataIn This C
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that benefits from being converted
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With this dataset in your workspace
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ange(cars$mpg)[1] 10.4 33.9Calculat
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As with most functions, you can sav
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Plotting histogramsTo get a clearer
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If this concept is unfamiliar to yo
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multiple variables, there’s a lot
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oxplot(mpg ~ cyl, data=cars)Figure
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Statisticians love it when they can
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You also can calculate the correlat
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with(cars, table(am, gear))3 4 5aut
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$ Var2: Factor w/ 2 levels “sick
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time specifying the margin argument
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Taking a Closer Look at Distributio
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Still, histograms leave much to the
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Now you want to do this for the tem
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Comparing Two SamplesComparing grou
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Again, you get the value for the te
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Many research questions revolve aro
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have to specify which margins you w
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str(InsectSprays)‘data.frame’:
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Checking the model tablesWith the m
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The difference between the means.Th
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The lm() function allows you to spe
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FunctionWhat It Doescoef()Returns a
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Model.anova Model.anovaAnalysis of
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predict(Model,newdata=new.cars, int
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Chapter 16Using Base GraphicsIn Thi
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The built-in R datasets are documen
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pch=21: Filled circlepch=22: Filled
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You also can use the function ablin
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It seems odd to use a plot function
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Figure 16-6: Adding main title, x-a
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Your graphic should look like Figur
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When your plot is complete, you nee
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getwd()[1] “C:/Users/Andrie”Nex
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Creating a Lattice PlotTo explore l
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Although cyl is a numeric vector, t
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into your R console.Changing Plot O
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xyplot(mpg ~ hp | factor(cyl), data
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Three-dimensional scatterplots: clo
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Notice that the function formula do
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millions of people. (The documentat
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Printing and Saving a Lattice PlotY
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Chapter 18Looking At ggplot2 Graphi
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aes() function to set up the mappin
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visual elements is the second eleme
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geom_point() Scatterplot stat_ident
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Creating line chartsTo create a lin
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Stat Description Default Geomstat_b
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Doing nothing with identitySometime
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Working with scalesIn ggplot2, scal
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Part VIThe Part of TensIn this part
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Then calculate the sum and mean for
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first supplied value as a fixed poi
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with(mtcars, length(mpg[hp > 150]))
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For example, to find the location o
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Your results should look similar to
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RGui and RStudio allow you to set t
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Reading the Package Manual and Vign
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Because the authors of R packages w
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AppendixInstalling R and RStudioBef
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a number of startup options by adap
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If you click Browse, you can select
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To access the cheat sheet specifica
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