rcc with p=1 or q=1

When using the function rcc with either X or Y containing a single column, the code runs fine. However, when we want to perform cross-validation using tune.rcc, we get the following error (here, X has a single column):

Error: 'X' must be a numeric matrix.

The traceback() is as follows:

6: stop("'X' must be a numeric matrix.", call. = FALSE)
5: rcc(X[-omit, ], Y[-omit, ], 1, lambda1, lambda2, method = "ridge")
4: Mfold(X, Y, lambda[1], lambda[2], folds, M)
3: FUN(newX[, i], ...)
2: apply(grid, 1, function(lambda) {
       Mfold(X, Y, lambda[1], lambda[2], folds, M)
   })
1: tune.rcc(X_mix, Y, grid1 = 0, grid2 = grid, validation = "Mfold", 
       M = 10)

The fix is therefore very straightforward: we need to replace

 rcc(X[-omit, ], Y[-omit, ], 1, lambda1, lambda2, method = "ridge")

with

 rcc(X[-omit, ,drop=FALSE], Y[-omit, ,drop=FALSE], 1, lambda1, lambda2, method = "ridge")

and similarly every time a subset of the rows is selected.

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