building a data.frame column wise

gistfile1.r

num.cols <- 10

# allocate space for your ten columns
cols <- vector('list', num.cols)

# add key column, such as timestamp
cols[[1]] <- 1:5

for (i in 2:num.cols) {
    cols[[i]] <- rnorm(5) # add the next column, 5 random numbers
}

# add the column names
names(cols) <- c('timestep', letters[1:9])

# convert the list to a data.frame
d <- data.frame(cols)