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NDL R Tutorial

author: Ryan Mears date: March 24, 2014 transition: linear

Overview

Working with data in R with the RStudio GUI

• Get and Shape data into tidy arrangements
• Analyze and Summarize data with R packages
• Explore and Present with data visualization and publication quality tables and plots

Installing R and RStudio

type: section

R

Install [R][R-prog] [R-Prog]: http://cran.us.r-project.org/

![The R Foundation for Statistical Computing][cranr] [cranr]: NDL_R_tutorial-figure/CranR.png "The R Foundation for Statistical Computing"

RStudio

Install [RStudio][RS-Prog] [RS-Prog]: http://www.rstudio.com/ide/download/desktop

![RStudio][cranr] [cranr]: NDL_R_tutorial-figure/rstudio-mac.png "RStudio"

Get and Shape Data

type: section

Reading Data and Code

• read.csv()

getwd()

• source()

getwd()

Data and Code in R

• data types
  • vectors
  • arrays and matrices
  • data frames
  • lists
• functions

Create variables

- c() ```{r} hc_subjs <- c('sbj101','sbj102','sbj105') sz_subjs <- c('sbj103','sbj104','sbj106') ``` - seq() - seq_len(6) `r seq_len(6) ` - seq(from = -2, to = 3, by = 1) `r seq(from = -2, to = 3, by = 1) ` - rep() - rep(c('HC','SZ'), times = 1, each = 3) `r rep(c('HC','SZ'), times = 1, each = 3) ` - rep(c('HC','SZ'), times = 3, each = 1) `r rep(c('HC','SZ'), times = 3, each = 1) `

Create variables

x <- seq_len(6)
subjs <- c(hc_subjs,sz_subjs)
cbind(x,subjs)

Create variables

• cbind()

  hc_2 <- cbind(hc_subjs,"hc")
  sz_2 <- cbind(sz_subjs,"sz")
  sz_2

---

• rbind()

 grp_subjs <- rbind(hc_2,sz_2)
  colnames(grp_subjs)<-c("subj","group")
  grp_subjs

Examine variables

• print()

print(hc_subjs)

• length()

length(hc_subjs)

• dim()

dim(grp_subjs)

---

• str()

str(grp_subjs)

Index and Select

• Indices

grp_subjs[1,1]
grp_subjs[1,]

---

• Booleans

grp_subjs[,2]=='hc'

Index and Select

• grep(), grepl(), gsub(), substr()

Convert and Combine

• paste(), paste0(), cat()
• join()
• expand.grid()

Subset and Reshape

• filter()
• select()
• reshape()
• melt()
• cast()
• **ply()

Analyze and Summarize

type: section

Compute Parameters

• mutate()

Compare Means

• ttest()

ANOVA

• ezANOVA()

plot(cars)

Explore and Present

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Plot

• plot()
• ggplot()
• ggvis()

Present Results for Publication

• stargazer()

Dynamic Documents

• knit()

Resources

type: subsection

• Papers
  • Tidy Data
  • Plyr (tutorials)
• Cheat Sheets
• R
• ggplot 1 & 2
• Matlab to R 1 & 2
• Wikis
  • ggplot2 & plyr & ggvis
  • Advanced R Programming

---

• Webpages
  • QuickR
  • Rseek & CRAN-R
• Books
  • GGPlot2
  • R in Action
  • The Art of R Programming
  • RStudio
  • Lattice
  • R in a Nutshell