Append data frames together in a for loop

Question

I have a for loop which produces a data frame after each iteration. I want to append all data frames together but finding it difficult. Following is what I am trying, please suggest how to fix it:

d = NULL for (i in 1:7) {    # vector output   model <- #some processing    # add vector to a dataframe   df <- data.frame(model)  }  df_total <- rbind(d,df) 

Answer 1

Don't do it inside the loop. Make a list, then combine them outside the loop.

datalist = list()  for (i in 1:5) {     # ... make some data     dat <- data.frame(x = rnorm(10), y = runif(10))     dat$i <- i  # maybe you want to keep track of which iteration produced it?     datalist[[i]] <- dat # add it to your list }  big_data = do.call(rbind, datalist) # or big_data <- dplyr::bind_rows(datalist) # or big_data <- data.table::rbindlist(datalist) 

This is a much more R-like way to do things. It can also be substantially faster, especially if you use dplyr::bind_rows or data.table::rbindlist for the final combining of data frames.

Answer 2

You should try this:

df_total = data.frame() for (i in 1:7){     # vector output     model <- #some processing      # add vector to a dataframe     df <- data.frame(model)     df_total <- rbind(df_total,df) }