I am adding together every third column and putting the result in a new column, I have to do this across a data frame with over 300 columns. I can make the loop to perform the addition but I'm having trouble with naming the new columns. Here's an example of what I want I have tried so var:
x1 <- rnorm(100)
x2 <- rnorm(100)
x3 <- rnorm(100)
x4 <- rnorm(100)
x5 <- rnorm(100)
x6 <- rnorm(100)
x7 <- rnorm(100)
x8 <- rnorm(100)
x9 <- rnorm(100)
x10 <- rnorm(100)
x11 <- rnorm(100)
x12 <- rnorm(100)
df <- data.frame(x1,x2,x3,x4,x5,x6,x7,x8,x9,x10, x11,x12)
for (i in 2:4){
new <- apply(df[,c(i,i+3,i+6)],1,sum,na.rm=T)
df <- cbind(df, new[i-1])
}
I would like the names of the new columns to appear as "new1", "new2" and "new3" however, with my code they are all named "new[i]. Please not that I am sure that there are other and perhaps better ways to create this columns without the use of a loop but I am specifically interested in finding out what is wrong with my loop and maintaining the use of it.Thanks
Replace the cbind to the following, and then you will be able to assign new column names.
for (i in 2:4){
new <- apply(df[,c(i,i+3,i+6)],1,sum,na.rm=T)
df[paste0("new", i-1)] <- new
}