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

Answer 1

Try to use rbindlist approach over rbind as it's very, very fast.

Example:

library(data.table)

##### example 1: slow processing ######

table.1 <- data.frame(x = NA, y = NA)
time.taken <- 0
for( i in 1:100) {
  start.time = Sys.time()
  x <- rnorm(100)
  y <- x/2 +x/3
  z <- cbind.data.frame(x = x, y = y)

  table.1 <- rbind(table.1, z)
  end.time <- Sys.time()
  time.taken  <- (end.time - start.time) + time.taken

}
print(time.taken)
> Time difference of 0.1637917 secs

####example 2: faster processing #####

table.2 <- list()
t0 <- 0
for( i in 1:100) {
  s0 = Sys.time()
  x <- rnorm(100)
  y <- x/2 + x/3

  z <- cbind.data.frame(x = x, y = y)

  table.2[[i]] <- z

  e0 <- Sys.time()
  t0  <- (e0 - s0) + t0

}
s1 = Sys.time()
table.3 <- rbindlist(table.2)
e1 = Sys.time()

t1  <- (e1-s1) + t0
t1
> Time difference of 0.03064394 secs