Re: [R] Averaging dataframes that are stored in a list

Hi, you could try the reshape package, l = list(d1= data.frame(ID=letters[1:4],value=1:4), d2= data.frame(ID=letters[1:4],value= -c(1:4))) library(reshape) m = melt(l) cast(m, .~ID, fun=mean) HTH, baptiste 2009/7/15 Mark Na mtb...@gmail.com Dear R-helpers, I have a list

[R] Averaging dataframes that are stored in a list

Dear R-helpers, I have a list containing 5000 elements, each element is a dataframe containing one ID column (identical over the 5000 dataframes) and 9 numeric variables, e.g. ID VAR1 VAR2 VAR3 ... VAR9 I would like to create a new dataframe containing the ID column and the mean values of the 9