I've got a simple question that I can't figure out: I would like to store matrices produced in a loop into one full storage matrix. For example, the following code generates a matrix 5x5 each iteration for three iterations but is unable to store them into one 5x15 matrix:

```
species_samp <- sample(unique(iris$Species))
store <- matrix(NA, ncol =5, nrow = 15)

for(i in 1:3){

    samp    <- iris[sample(nrow(iris[iris$Species==species_samp[i],]), 5),]
    store[i,] <- samp
}   

```

This fails, however I would like to ultimately have a store matrix with the the full matrix that gets sampled in each iteration of the loop. Any and all help appreciated. Thanks.