Differences

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--- r:data_transformations [2016/10/12 08:59] – [Applying a Function to Groups of Rows] hkimscil
+++ r:data_transformations [2019/09/19 18:23] (current) – [Splitting a Vector into Groups] hkimscil
@@ Line 6: / Line 6: @@
 Warning message:
 패키지 ‘MASS’는 R 버전 3.2.5에서 작성되었습니다
-> split(Cars93$MPG.city, Cars93$Origin)
+> split(Cars93$MPG.city, Cars93$Origin) # Origin별로 MPG.city를 나눠라
 $USA
  [1] 22 19 16 19 16 16 25 25 19 21 18 15
@@ Line 39: / Line 39: @@
 [1] 23.86667
 >
+# or
+> sapply(g, mean)
+     USA  non-USA
+.95833 23.86667
+# or retain list format
+> lapply(g, mean)
+$USA
+[1] 20.95833
+$`non-USA`
+[1] 23.86667
 </code>
 ====== Applying a Function to Each List Element ======
@@ Line 180: / Line 193: @@
 <code>suburbs <- read.csv("suburbs.csv", head=T, sep="	")
+suburbs <- read.csv("http://commres.net/wiki/_export/code/r/data_transformations?codeblock=15", head=T, sep="	")
 </code>
@@ Line 246: / Line 260: @@
               (Other)   :21
 </code>
+<code>tapply(suburbs$pop, suburbs$state, summary)
+</code>
+<code>by(suburbs$pop, suburbs$state, summary)
+</code>