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notes:r_cheat_sheet [2026/06/04 21:04]
47.79.10.230 old revision restored (2026/05/30 10:47) 		notes:r_cheat_sheet [2026/06/07 09:38] (current)
138.204.211.184 old revision restored (2014/10/05 03:25)
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   * ''myseq[3]'' to access third element i.e. vectors indexed starting at 1.   * ''myseq[3]'' to access third element i.e. vectors indexed starting at 1.
   * Use a vector as an index to access multiple elements e.g. ''myseq[c(1,3)]''   * Use a vector as an index to access multiple elements e.g. ''myseq[c(1,3)]''
-  * The ''names'' function can be used to assign names to vector elements. Once names are asigned, they can be sed as indices e.g. <code>+  * The ''names'' function can be used to assign names to vector elements. Once names are asigned, they can be used as indices e.g. <code>
 names(myseq)=c('one','two','three') names(myseq)=c('one','two','three')
 myseq['two']</code> myseq['two']</code>
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   * 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)
  
 +===== Data Sets =====
 +  * ''factor'' is a collection type for categorized values - ''myfac=factor(myvec)''
 +  * ''factor''s group unique string values as ''level''s e.g. levels(myfac) shows unique levels. 
 +  * ''as.integer(myfac)'' shows levels as integers, can be used to set plot type
 +  * ''legend("to­pright", level­s(types), pch=1­:length(le­vels(types­)))''
 +  * A data frame collects sets of related values (i.e. sets of columns with values in the same order) e.g. ''mydf=data.frame(weights,prices,types)''
 +  * To extract a column, use double-square brackets with the column index or name e.g. ''mydf%%[['weights']]%%'' or just a dollar sign e.g. ''treasure$prices''
 ===== Plotting ===== ===== Plotting =====
  
-  * ''barplot[myseq]'' creates a bar plot of the ''myseq'' vector.+  * ''barplot[myseq]'' creates a bar plot of the ''myseq'' vector. ''abline(h=y)'' plots a horizontal line at height y.
   * ''plot[x,y]'' plots x vs y e.g. <code>   * ''plot[x,y]'' plots x vs y e.g. <code>
 x=seq[0,20,.1] x=seq[0,20,.1]
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   * ''mymatrix[,2]'' returns entire second column.   * ''mymatrix[,2]'' returns entire second column.
  
 +===== Statistics =====
 +
 +  * ''mean(myvec)  median(myvec)   sd(myvec)''
 ===== File Handling ===== ===== File Handling =====
  
   * ''list.files()'' to list files in furrent directory   * ''list.files()'' to list files in furrent directory
   * ''source("file.R")'' to load file of code   * ''source("file.R")'' to load file of code
 +  * ''read.csv('mydat.csv')'' to load a csv file
notes/r_cheat_sheet.1780632244.txt.gz · Last modified: 2026/06/04 21:04 by 47.79.10.230

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