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--- notes:r_cheat_sheet [2026/07/30 13:17]
114.119.158.118 old revision restored (2026/06/30 13:46)
+++ notes:r_cheat_sheet [2026/07/31 18:55] (current)
47.254.159.162 old revision restored (2026/06/07 07:45)
@@ Line 11: / Line 11: @@
   * Booleans are e.g. ''1=1'' , ''3>4'' , ''TRUE'', T, ''FALSE'', F
   * 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 ''+ - * / = <-''
   * ''NA'' is used to express a missing or unknown data  value. Expressions on NA return NA.
@@ Line 26: / Line 26: @@
   * ''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)
+  * ''head(myvec)'' , ''tail(myvec)'' to show start or end of vector
 ===== Plotting =====
@@ Line 37: / Line 38: @@
   * ''persp(mymat)'' plots a contour map in perspective.
   * ''image(volcano)'' generates a heat map of the matrix.
+  * ''qplot(weights, prices, color=types)'' - more attractive plotting using ggplot2 package.
 ===== Matrices =====
@@ Line 67: / Line 68: @@
   * ''read.csv('mydat.csv')'' to load a csv file
   * ''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 an array of lines

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