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--- notes:r_cheat_sheet [2026/09/14 05:19]
165.99.194.174 old revision restored (2026/08/28 13:02)
+++ notes:r_cheat_sheet [2026/09/16 10:28] (current)
216.73.216.94 old revision restored (2026/09/14 11:20)
@@ Line 20: / Line 20: @@
   * ''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)]''
-  * 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>
+  * 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>
 names(myseq)=c('one','two','three')
 myseq['two']</code>
@@ Line 28: / Line 28: @@
 ===== Plotting =====
-  * ''barplot[myseq]'' creates a bar plot of the ''myseq'' vector. ''abline(h=y)'' plots a horizontal line at height y.
+  * ''barplot[myseq]'' creates a bar plot of the ''myseq'' vector.
   * ''plot[x,y]'' plots x vs y e.g. <code>
 x=seq[0,20,.1]
@@ Line 35: / Line 35: @@
   * ''contour(mymat)'' plots a contour map of a matrix.
   * ''persp(mymat)'' plots a contour map in perspective.
-  * ''image(volcano)'' generates a heat map of the matrix.
 ===== Matrices =====
@@ Line 43: / Line 42: @@
   * dim(myseq) can be used to change dimensions of a matrix
   * ''mymatrix[3,4]'' returns an element of the matrix (row,column).
-  * ''mymatrix[,2]'' returns entire second 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''
-  * ''merge'' merges data sets by joining on shared column names
-===== Statistics =====
-  * ''mean(myvec)  median(myvec)   sd(myvec)''
-  * ''cor.test'' tests for correlation (Pearson's product-moment)
-  * ''line = lm(cola ~ colb)'' calculates a linear model between cola and colb that can be plotted with ''abline(line)''
-  *
 ===== 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
-  * ''read.table'' to read text data with other separators

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