search for: cars2

...the two DFs based on this unique ID. Is there a better way? Many thanks for your help, Mark #compare two dataframes and extract uncommon rows #MAKE SOME DATA cars$id<-paste(cars$speed,cars$dist,sep="") $create unique ID field by pasting all columns together cars1<-cars[1:35,] cars2<-cars[16:50,] #EXTRACT UNIQUE ROWS cars1_unique<-cars1[cars1$id %in% setdiff(cars1$id,cars2$id),] #rows unique to cars1 (i.e., not in cars2) cars2_unique<-cars2[cars2$id %in% setdiff(cars2$id,cars1$id),] #rows unique to cars2

I have a large data frame 48:2185 with different numbers. I would like to add only one row at the very top of my data frame with 0's or NA's. I don't know which approach to use. Should i create 2 different data frames and merge them? Ive also tried the rbind command with no luck. I would appreciate some help to achieve what I'm trying to create. Thanks!

...rix. The beginning of my code is: Cars <- read.csv(filename, header=TRUE, row.names=NULL, sep=";") attach(Cars) n <- as.numeric(n) s <- as.numeric(s) # et cetera, the other variabeles are declared as numeric or as factors # I've tried to extract the data the following way: Cars2 <- Cars[Cars$s!=0] #However, then I get the error message: Error in `[.data.frame`(Cars, Cars$s != 0) : undefined columns selected # If I try s[s!=0] # I do get the positive s-values, but how can I get all colums in a matrix? Does anyone know how this can be done? Your help would be greatly...