[R] new column that applies function to all rows based on last row

[arun]

HI BNC,

For the example you provided:
CHAR1n_totalNew <- within(CHAR1n_total,Newvar <- (Freq/tail(Freq,1))*100)
#If you have more than one column
#For example
set.seed(42)
 Freq2 <- sample(4,10,replace=TRUE)
 CHAR1n_total$Freq2 <- c(Freq2,sum(Freq2))


 dat2 <- as.data.frame(matrix(NA,ncol=((ncol(CHAR1n_total)-1)*2)+1,nrow=nrow(CHAR1n_total)))
dat2[,1] <- CHAR1n_total[,1]
dat2[,seq(2,ncol(dat2),by=2)] <- CHAR1n_total[,-1]
 dat2[,seq(3,ncol(dat2),by=2)] <- t((t(CHAR1n_total[,-1])/unlist(tail(CHAR1n_total[,-1],1)))*100)
dat2
##You can change the names of the columns accordingly.

A.K.


I know this is a simple question, but I am having trouble generating 
output without errors.  I want to create a column containing values for 
each row that are generated by dividing another column's row value by 
the same column's sum (last-row value): 



Here is the (less-than-elegant) practice script I'm working with (minus the code generating errors): 

mydata <- data.frame (CaseID = c("1","2","3","4","5","6","7","8","9","10","11","12","13","14"), 
          EstablishmentEEs = c(3,3,4,5,8,8,9,10,10,11,12,12,13,14)) 

freqdata.1n <- mydata$EstablishmentEEs 
CHAR1n <- table(freqdata.1n) 
CHAR1nmatrix <- as.data.frame(CHAR1n) 
rownames(CHAR1nmatrix) <- CHAR1nmatrix$freqdata.1n 
CHAR1n_total <- addmargins(as.table(as.matrix(CHAR1nmatrix[-1])), 1) 
CHAR1n_total <- as.data.frame(CHAR1n_total) 
CHAR1n_total <- subset(CHAR1n_total, select= -Var2) 
library(gdata) 
CHAR1n_total <- rename.vars(CHAR1n_total,from="Var1",to="freqdata.1n",info=FALSE) 

Thanks for your patience!