I have a large 2D matrix that is 1000 x 1000. I want to reshape this so that it is one column (or row). For example, if the matrix was:
A B C
1 4 7
2 5 8
3 6 9
I want to turn it in to:
1 2 3 4 5 6 7 8 9
I do not need to preserve the column headers, just the order of the data. How do I do this using reshape2 (which is the package that I presumed was the easiest to use)?
Just to clarify, I mentioned reshape as I thought it was the best way of doing this. I can see that there are simpler methods which I am perfectly happy with.
Answer
I think it will be difficult to find a more compact method than:
c(m)
[1] 1 2 3 4 5 6 7 8 9
However, if you want to retain a matrix structure, then this reworking of the dim attribute would be be effective:
dim(m) <- c(dim(m)[1]*dim(m)[2], 1)
m
[,1]
[1,] 1
[2,] 2
[3,] 3
[4,] 4
[5,] 5
[6,] 6
[7,] 7
[8,] 8
[9,] 9
There would be more compact methods of getting the product of the dimensions but the above method emphasizes that the dim attribute is a two element vector for matrices. Other ways of getting the "9" in that example include:
> prod(dim(m))
[1] 9
> length(m)
[1] 9