R 1.2.1 - read.table - factors problem or is it a data.frame problem

However, the problem encountered is not one of setting factors but of unsetting
them. The manual states that variables of mode or type character will become
factors. My data input efforts showed no relationship between type and factor.
With no evident reason, most character variables did not become factors while
many real variables did. It is a bit disconcerting to get an output with
thousands of floating point factor levels or error messages that one's data are
of the wrong mode for any analysis whatsoever.

How does one unset mode assignment of factor and how does one avoid the problem
of automatic misassignment with other datasets?

You can convert a factor to the correct numeric values with
   as.numeric(as.character(the.factor))

We don't have enough information to tell what happened in your case but in
my experience the most common reason for a numeric variable to read as a
factor has been misspecifying the missing value codes in the na.strings
argument. This argument lists the strings that should be converted to NAs;
any other strings will trigger a conversion to factor.

	-thomas

Thomas Lumley			Asst. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle

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