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--- notes:r_cheat_sheet [2026/06/12 11:38]
101.47.26.62 old revision restored (2026/05/31 04:42)
+++ notes:r_cheat_sheet [2026/06/13 19:09] (current)
188.235.16.74 old revision restored (2026/06/05 07:31)
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   * ''mymatrix[3,4]'' returns an element of the matrix (row,column).
   * ''mymatrix[,2]'' returns entire second column.
-===== 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''
 ===== Statistics =====
   * ''mean(myvec)  median(myvec)   sd(myvec)''
 ===== File Handling =====
   * ''list.files()'' to list files in furrent directory
   * ''source("file.R")'' to load file of code
-  * ''read.csv('mydat.csv')'' to load a csv file

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