character to numeric

["Frank Lawrence" <Cougar@psu.edu>]

I have multiple data files [ASCII format]. Each file is sequentially
numbered and contains a combination of text and numbers.  My interest in
the text is only to identify rows. I want the rows that begin with 'I'
or 'S'.  There are multiple occurrences of the 'I' and 'S' rows in each
data file.  I want to extract the numbers in those rows that begin with
'I' or 'S' for further analysis.  Each row of interest contains 8
columns of numbers.  I would like to put those columns of numbers in 8
separate columns of a data frame.  Furthermore, I would like to put in a
row of "NA" if the row does not exist in the data file.


Respectfully, 
Frank R. Lawrence