[R] Problems with numeric variable containing ? values

[ftorrei2@uiuc.edu]

Hello,

I have a problem with the values for one column in a table.
The variable represented in this column is numeric (I get TRUE
when I ask is.numeric(x)). However, the values are listed
ordinally and with row numbers as values, not with the ones
that appear in the table. Some rows have an undefined value
for this column, which appears as ? in the table (this is not
an error). I wonder whether these undefined values are causing
the problem.
I need to extract a subset from this column with all rows not
having '?' and then use the subset for a number if analysis.
So far this is not possible since the subset does not have the
real values, but the row numbers mentioned above. Any help?

Thanks in advance,
Francisco Torreira     
Francisco Torreira
Spanish, Italian and Portuguese
Univ. of Illinois at Urbana-Champaign
707 South Mathews Aven.
4031 FLB
Urbana, IL, 61801