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--- r:data_structures [2019/09/19 17:53] – [Mode: Physical Type] hkimscil
+++ r:data_structures [2019/09/19 18:16] (current) – [Creating a Factor (Categorical Variable)] hkimscil
@@ Line 54: / Line 54: @@
 ^ Object  ^ Example  ^ Mode  ^
-| Number  | 3.1415  | numeric  |
+| Number  | ''%%3.1415%%''  | numeric  |
-| Vector of numbers  | c(2.7.182, 3.1415)  | numeric  |
+| Vector of numbers  | ''%%c(2.7.182, 3.1415)%%''  | numeric  |
-| Character string  | "Moe"  | character  |
+| Character string  | ''%%"Moe"%%''  | character  |
-| Vector of character strings  | c("Moe", "Larry", "Curly")  | character  |
+| Vector of character strings  | ''%%c("Moe", "Larry", "Curly")%%''  | character  |
-| Factor  | <code>factor(c("NY", "CA", "IL"))</code>  | numeric  |
+| Factor  | ''%%factor(c("NY", "CA", "IL"))%%''  | numeric  |
-| List  | list("Moe", "Larry", "Curly")  | list  |
+| List  | ''%%list("Moe", "Larry", "Curly")%%''  | list  |
-| Data frame  | data.frame(x=1:3, y=c("NY", "CA", "IL"))  | list  |
+| Data frame  | ''%%data.frame(x=1:3, y=c("NY", "CA", "IL"))%%''  | list  |
-| Function  | print  | function  |
+| Function  | ''%%print%%''  | function  |
 ===== Class =====
@@ Line 135: / Line 135: @@
 Grouping: This is a technique for labeling or tagging your data items according to their group. See the Introduction to Chapter 6.
+<code>> A <- c(1,2,2,3,3,4,4,4,4,2,1,2,3,3)
+> A
+ [1] 1 2 2 3 3 4 4 4 4 2 1 2 3 3
+> str(A)
+ num [1:14] 1 2 2 3 3 4 4 4 4 2 ...
+> fA <- factor(A)
+> fA
+ [1] 1 2 2 3 3 4 4 4 4 2 1 2 3 3
+Levels: 1 2 3 4
+> str(fA)
+ Factor w/ 4 levels "1","2","3","4": 1 2 2 3 3 4 4 4 4 2 ...
+>
+</code>
 ===== Data Frames =====
@@ Line 227: / Line 241: @@
 [1] 11 12 13 14 15 16
 </code>
-<WRAP box help>The above code is very useful. But, sometimes the recycling rule is very annoying. How would I avoid it?
-</WRAP>
 ====== Creating a Factor (Categorical Variable) ======
@@ Line 252: / Line 263: @@
 <code>> f <- factor(wday, c("Mon","Tue","Wed","Thu","Fri")) # c(...) part means "levels" not data
-> f
+> f  # note that there is no Fri in the below output.
  [1] Wed Thu Mon Wed Thu Thu Thu Tue Thu Tue
 Levels: Mon Tue Wed Thu Fri