[R] factor matrix

Adrian Baddeley adrian at maths.uwa.edu.au
Fri Dec 3 06:45:19 CET 2004

Sorry if this is a FAQ.

Is there a good reason why a factor has to be
a one-dimensional vector and cannot be a matrix? 

I want to construct matrices of categorical values. 

Vain attempts like
   matrix(factor(c(T,F,F,T), 2,2) 
yield a matrix of character strings representing the factor levels, 
not the levels themselves, while 
   factor(matrix(c(T,F,F,T), 2,2))  
converts the matrix to a logical vector of length 4
then converts the vector to a factor.

Adrian Baddeley

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