[R] Indexing a loop-created list

Nicolas Prune np at alambic.org
Wed Oct 18 17:08:20 CEST 2006


Hello,

I create a certain number (n*m) matrices, that I would like to store. These
matrices have different dimensions. As far as I know, for matrices of different
dimensions, there's no alternative to a list.

Here's how I store them on the fly :

my_list <- NULL

for (i in 1:n)
	{for (j in (i+1):m)
		{my_list <- list(my_list,i_create_a_matrix(i,j)))
	}
}

But the indexation of the result is horrible ! (see below a simplified version,
with no matrices created but i*10+j added to the list instead). Is there a
cleaner way to get the same result ?

Any help will be very welcomed.
Nicolas

[[1]]
[[1]][[1]]
[[1]][[1]][[1]]
[[1]][[1]][[1]][[1]]
[[1]][[1]][[1]][[1]][[1]]
[[1]][[1]][[1]][[1]][[1]][[1]]
NULL

[[1]][[1]][[1]][[1]][[1]][[2]]
[1] 12


[[1]][[1]][[1]][[1]][[2]]
[1] 13


[[1]][[1]][[1]][[2]]
[1] 14


[[1]][[1]][[2]]
[1] 23


[[1]][[2]]
[1] 24


[[2]]
[1] 34



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