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notes:r_cheat_sheet [2014/10/05 17:30]
smthng [Statistics]
notes:r_cheat_sheet [2015/01/10 15:25] (current)
smthng [File Handling]
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   * ''R'' is the command-line interpreter   * ''R'' is the command-line interpreter
 +  * ''install.pa­ckages("gg­plot2") '' to install additional packages
 +
   * Expressions are evaluated and displayed e.g. 1, 1+1, "Hello World"   * Expressions are evaluated and displayed e.g. 1, 1+1, "Hello World"
   * Booleans are e.g. ''1=1'' , ''3>4'' , ''TRUE'', T, ''FALSE'', F   * Booleans are e.g. ''1=1'' , ''3>4'' , ''TRUE'', T, ''FALSE'', F
   * For variable assignment ''x=1'' or ''x<-1''   * For variable assignment ''x=1'' or ''x<-1''
-  * For help on a function use ''help(sum)'' or ''example(sqrt)''+  * For help on a function use ''help(sum)'' ,  ''help(package='ggplot2')''  or ''example(sqrt)''
   * Operations are ''+ - * / = <-''   * Operations are ''+ - * / = <-''
   * ''NA'' is used to express a missing or unknown data  value. Expressions on NA return NA.   * ''NA'' is used to express a missing or unknown data  value. Expressions on NA return NA.
- 
 ===== Vectors ===== ===== Vectors =====
   * To create a vector, use the combine command ''c(4,7,9)''   * To create a vector, use the combine command ''c(4,7,9)''
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   * ''myseq + 1'' adds one to all elements of the myseq vector.   * ''myseq + 1'' adds one to all elements of the myseq vector.
   * Scalar operations or functions on vectors typically produce other vectors e.g. + - == sin(myseq)   * Scalar operations or functions on vectors typically produce other vectors e.g. + - == sin(myseq)
 +  * ''head(myvec)'' , ''tail(myvec)'' to show start or end of vector
  
 ===== Plotting ===== ===== Plotting =====
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   * ''persp(mymat)'' plots a contour map in perspective.   * ''persp(mymat)'' plots a contour map in perspective.
   * ''image(volcano)'' generates a heat map of the matrix.   * ''image(volcano)'' generates a heat map of the matrix.
 +  * ''qplot(weights, prices, color=types)'' - more attractive plotting using ggplot2 package.
 ===== Matrices ===== ===== Matrices =====
  
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   * ''read.csv('mydat.csv')'' to load a csv file   * ''read.csv('mydat.csv')'' to load a csv file
   * ''read.table'' to read text data with other separators   * ''read.table'' to read text data with other separators
 +  * ''con<-url("http://google.com","r")'' to read a webpage
 +  * ''x<-readLines(con)'' to convert to a vector of lines
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