[R] as.data.frame(cbind()) transforming numeric to factor?

[Prof Brian Ripley]

On Fri, 18 Aug 2006, Tom Boonen wrote:

> Dear List,
> 
> why does as.data.frame(cbind()) transform numeric variables to
> factors, once one of the other variablesused is a character vector?
> 
> #
> x.1 <- rnorm(10)
> x.2 <- c(rep("Test",10))
> Foo <- as.data.frame(cbind(x.1))
> is.factor(Foo$x.1)
> 
> Foo <- as.data.frame(cbind(x.1,x.2))
> is.factor(Foo$x.1)
> #
> 
> I assume there is a good reason for this, can somebody explain? Thanks.

Only if you can explain the good reason why you did not just use 
data.frame(x.1, x.2)!

cbind() makes a matrix out of vectors, here a character matrix.  And then 
as.data.frame() converts character columns to factors.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
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