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I would like to populate a matrix with values from user defined lists (this part is not important yet). The selection from these lists should be random without replacement until the list is exhausted.

For example, if we have list_1 <- c(1,2,3) and list_2 <- c('a', 'b', 'c')

The (1,1) element of the matrix is drawn from the list_1 with the 2 assigned. The (1,2) element draws from list_1 and is assigned 3 (2 is not available as it has already been assigned). The (1,3) element draws from list_2 and is assigned 'b'. The element (2,1) also draws from list_1 and is assigned 2 as this is the only remaining element in list_1. This would continue until all elements within the matrix have been assigned a value. There are an equal number of elements in the matrix as there are in the lists (in total).

Given the structure of the matrix, I am not able to simply use the C() function to combine a number of vectors and randomise within each vector.

As I am a R novice, please forgive me if the above explanation is not clear.

Thanks in advance for any help.

EDIT: The rationale for the specific position within the matrix is that the matrix represents a experimental design. Each position in the matrix might represent a small plot of soil. Each list might represent a different type of seed and the elements within each list variations on the seed type. List_1 might all flower seeds (Rose, Daisy, etc.) and List_2 might contain all herb seeds (Parsley, Origano, etc.). I want to constrain the type of seed that can be planted in a particular plot. The seed that is actually allocated to that plot, is then randomly selected from the seed list. Some plots are allowed to contain a randomly allocated flower seed, but not a herb seed.

As I don't want to end up with all roses, for example, once a rose seed has been allocated to a plot, that seed option should be removed from the list.

For example (1,1) might be a 'flower' plot, a seed will be randomly selected from the flower list, after this process, and a daisy seed is assigned to (1,1). We then move on to the next 'flower' plot, but now the daisy seed is not available for assignment as it is not in the list (as it has already been assigned to (1,1)).

I hope this makes more sense.

SNA14L
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    A `matrix` can only have on class object within it, in this case either `integer` or `character`. If you change your lists so that they are all the same (perhaps all `character`), then `matrix(sample(c(list_1, list_2)), ncol=2)` would get you the whole matrix. I don't see any intention or rationale for which list is referenced for which matrix position; if there is one, please [edit] your question and provide some clarity. Thanks! – r2evans Jun 16 '20 at 03:52
  • Take a look at the [arrangements](https://randy3k.github.io/arrangements/) package. I think that will give you simple ways of getting what you want. +1 to @r2evans' comments about matrices and reproducibility. – Limey Jun 16 '20 at 06:51
  • Thank you both so much!! I will give that a try. – SNA14L Jun 17 '20 at 01:41

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