R Programming

Pros:

• Open source
• Abundant statistical packages
• Simplicity
• Data visualization
• Nice IDE

Cons: it could be Slow

• Interpreted language
• Memory management

• Object size: object_size()

  • Every length 0 vector occupies 40 bytes of memory.

• Memory usage and garbage collection: mem_used(), mem_changed()

• Modification in place

  • Primitive vs non-priminitive functions
  • for loops could be slow

Download regular release, or preview version

• Control R version
• vim editor
• Change theme
• Version control with Git or SVN
• Create a project and an R script
• Save workspace and changed script
• Documents
  • pdf: LaTex, Sweave, Knitr
  • html: R markdown, Rpres, Notebook
• Web application: Shiny

Useful shortcut for writing R script:

• Ctrl+Space or Tab: show information of the function
• Tab: give you the details of the argument
• Ctrl+Shift+c: add or remove comment “#”
• While executing code, the environment tab shows the objects in your current environment
• Ctrl+R or Ctrl+Enter: executing the code
• Source and Source on save: useful for editing function
• Debuging (more details on Thursday)

• Indentation
• Assignment (use <- , not = )
• Line Length (80 characters prefered)
• Comment your code
• Naming Convention

Be consistent!

• all lower case: searchpaths …

• period separated: as.numeric, read.table …

• underscore separated: package_version …

• lower camel case (suggested): colSums, sessionInfo …

• Upper camel case: Vectorize, NextMethod …