adding rows as arithmatic calculation on original rows
This should get you close:
x <- read.table(textConnection("myID myType myNum1 myNum2 myNum3
+ a Single 10 11 12 + b Single 15 25 35 + c Double 22 33 44 + d Double 4 6 8"), header=TRUE)
closeAllConnections()
y <- lapply(split(x, x$myType), function(.type){
+ .means <- colMeans(.type[,3:5]) + # create the new line for the data frame + .df <- data.frame(myID='', myType=.type$myType[1], myNum1=.means[1], + myNum2=.means[2], myNum3=.means[3]) + rbind(.type, .df) # append the line to the original dataframe + })
do.call(rbind, y) # you can add the names your want
myID myType myNum1 myNum2 myNum3 Double.3 c Double 22.0 33.0 44.0 Double.4 d Double 4.0 6.0 8.0 Double.myNum1 Double 13.0 19.5 26.0 Single.1 a Single 10.0 11.0 12.0 Single.2 b Single 15.0 25.0 35.0 Single.myNum1 Single 12.5 18.0 23.5
On Fri, Dec 5, 2008 at 3:21 PM, Ferry <fmi.mlist at gmail.com> wrote:
Dear R users,
Suppose I have the following data.frame:
myID myType myNum1 myNum2 myNum3
a Single 10 11 12
b Single 15 25 35
c Double 22 33 44
d Double 4 6 8
and I want to have new records:
myID myType myNum1 myNum2 myNum3
e Single 12.5 18 23.5
f Double 13 19.5 28
where record e got its myNum1-3 as the average from record a and b, and
record f got its myNum1-3 as the average from record c and d.
and the final data.frame should be like the following:
myID myType myNum1 myNum2 myNum3
a Single 10 11 12
b Single 15 25 35
e Single 12.5 18 43.5
c Double 22 33 44
d Double 4 6 8
f Double 13 19.5 28
Any idea is appreciated. Thanks beforehand.
Ferry
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