R

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R

• Roger Barlow
• HEP Computing seminar
• 21st February 2008

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What is R?

• A data handlinggraphics system with particular
  emphasis on statistical tools
• Compare and contrast PAW, Root, Easyplot, Matlab

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Getting hold of R

• Google R download and follow instructions
• Quite painless
• Windows and unix versions exist

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Philosophy

• 1.1 The R environment
• R is an integrated suite of software facilities
  for data manipulation, calculation and graphical
  display. Among other things it has
• an effective data handling and storage
  facility,
• a suite of operators for calculations on
  arrays, in particular matrices,
• a large, coherent, integrated collection of
  intermediate tools for data analysis,
• graphical facilities for data analysis and
  display either directly at the computer or on
  hardcopy,
• and
• a well developed, simple and effective
  programming language (called S) which includes
  conditionals, loops, user defined recursive
  functions and input and output facilities.
  (Indeed most of the system supplied functions are
  themselves written in the S language.)
• The term environment is intended to
  characterize it as a fully planned and coherent
  system, rather than an incremental accretion of
  very specific and inflexible tools, as is
  frequently the case with other data analysis
  software.

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What do you get?
Help button Gives help And manuals
Command line for entering instructions
Screen where plots appear
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Example simple stuff
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Assignment and vectors
c means concatenate
Assignment operators
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Plotting
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Arguments

• Type help
• (ltwhatevergt)
• Eg
• help(rnorm)

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More plotting
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Other plots
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Functions and scripts
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What was in the source file

• print("Loading Fourier routines")
• PIBY2lt-asin(1) PIlt-2piby2 TWOPI2PI
  ROOT2PIsqrt(TWOPI)
• alternationlt-function(n) 2(seq(1n) 2)- 1
• fourierlt-function(data,lo,hi)
• nbins lt- length(data)
• nnround(nbins/2)
• W lt- hi-lo
• delta lt- W /nbins
• iilt-seq(1,nbins)-1
• xlt-deltaiilo
• thetalt-xtwopi/W
• fclt-seq(1,nn)
• fslt-seq(1,nn)
• for(i in seq(1,nn))
• fcilt- sum(cos(itheta)data)
• fsilt- sum(sin(itheta)data)
• fcnnfcnn/2
• fsnn0

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Files and stuff

• For hardcopy
• gtpostscript(ltfilenamegt)
• gt plotting
• gtdev.off()
• Also png(ltfilenamegt) and others
• File input
• gtsread.table(ltfilenamegt")
• gtprint(sV1)
• gtplot(sV1,sV2)
• etc
• Or read.table(ltfilenamegt,HEADERTRUE)
• And first line of file will be taken as names
  used instead of V1, V2

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Interested?

• Type demo() at the prompt