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An Introduction to the R Statistical Programming Language

An Introduction to the R Statistical Programming Language. Timothy J. Robinson University of Wyoming tjrobin@uwyo.edu and Doug Nychka (add info). Some material from NY Times, various Harry Potter websites, Matthew Keller (www.mckeller.com), Revolution Analytics, and Ian Westbrooke (NZDOC).

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An Introduction to the R Statistical Programming Language

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  1. An Introduction to the RStatistical Programming Language Timothy J. Robinson University of Wyoming tjrobin@uwyo.edu and Doug Nychka (add info) Some material from NY Times, various Harry Potter websites, Matthew Keller (www.mckeller.com), Revolution Analytics, and Ian Westbrooke (NZDOC)

  2. What is R? A. 18th letter of the alphabet B. Rating for movies that suggests our kids should refrain from watching C. Favorite pirate saying • Fastest growing statistical software package in the world • All of the above

  3. Users of R • Google, Pfizer, Merck, Bank of America, Procter & Gamble, GE, Shell, Intercontinental Hotels, IBM, Hewlett-Packert, and many others • National laboratories (Los Alamos, Sandia, and others), U.S. Fish and Wildlife Service, U.S.G.S., U.S. Department of Treasury, and many others • Growing number of academic institutions in the U.S. and around the world • In January 2009, estimated that over 2 million users of R worldwide

  4. Where did it come from? • First appeared in 1996 when professors Ross Ihaka and Robert Gentleman, University of Auckland in New Zealand released the code as a free software package • John Chambers, Bell Labs Researcher and currently a consultant for the Department of Statistics at Stanford, was an early champion of R. Chambers was part of the development team for SPLUS • Recently, Revolution Analytics has developed a platform for enabling R to handle massive data sets • NY Times 2009 suggested that R is rivaling the biggest stat software company of all, SAS…the response of SAS in the article:

  5. Loading R • Go to http://cran.r-project/ • R for Windows screen, double-click “base” • Find, click on download R …save the executable file • Double-click the executable file to get into the installation wizard • When finished, you will have the R-icon for the particular version on your desktop

  6. At http://cran.r-project.org/

  7. After Double-Clicking on R icon

  8. The R Prompt (>) • > This is the “R prompt.” It says R is ready to take your command • R as a calculator : • > 5+2 • > 6^2 • > sqrt(16) • Creating a data set: • > flowers <- c(1.2, 2.6, 3.4, 2.9,5.1) • > flowers • The above line tells R to print the data set “flowers” Red denotes commands Blue denotes output

  9. Important Rules • We created a variable • Variable names are case sensitive • No blanks in name (can use _ or . to join words, but better not to use a blank between names) • Start with a letter (cap or lc) • Use of <- instead of =

  10. Non-Numeric Data • Enclose in quotes, single or double • Separate entries with comma • Example: > names = c(“Tim”, “Dawn”, “Ian”, “Rosamund”, “Jay”)

  11. Common Statistics Functions in R functioncalculates this mean ( ) mean median ( ) median mode ( ) mode sd ( ) standard deviation range ( ) range IQR ( ) interquartile range min ( ) minimum value max ( ) maximum value cor ( ) correlation quantile ( ) percentile length( ) sample size

  12. R, And the Rise of the Best Software Money Can’t Buy R programming language is a lot like magic... except instead of spells you have functions.

  13. Fathom, MINITAB, SAS, etc. users are like muggles: - can’t change their environment - rely on algorithms which are ‘canned’ - rely on the output provided - have to pay to constraining algorithms.

  14. = wizard “R users are like wizards. They can rely on functions (spells) that have been developed for them by statistical researchers, but they can also create their own. They don’t have to pay for the use of them, and once experienced enough (like Dumbledore), they are almost unlimited in their ability to change their environment.” Matthew Keller

  15. What Drives the Capability of R? • Installed packages/libraries • The base installation includes many packages/libraries but you can supplement the base installation with other packages/libraries

  16. Just scroll down to one of the many USA sites

  17. Learning R....

  18. R-help listserve....

  19. Rcmdr • It is a package in R • Advantages: • Click on the menu – similar to SPSS, Minitab, JMP • No need to memorize the R-functions • Save the script in your personnel directory and use it for future. • Good for non-statistical people or folks just starting use of R • Disadvantages: • No access for some functions • Limited access to the packages • Does not always help those with limited statistical skills enough

  20. Installing Rcmdr Choose the Rcmdr package and click OK

  21. Installing vs. Loading a Package/Library • ‘Installing’ a package involves getting your machine to talk to a CRAN server and downloading the package/library from the CRAN site to your personal machine • Once the package is installed, we must load the package in order to activate it for our current session…this can be accomplished in one of two ways: - Use the library( ) function - Use the drop-down menu from the console window

  22. You now have a “point and click” environment within which to operate

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