Thanks Peter.  It works with read.delim.

David: Thanks for your comments.  To answer your questions.  I don't have
'NA' and all balanced.  The number of mssing levels were 4 and it happened
only to those four levels.  Yes, there is commas embedded and some
characters (e.g., '-', space, some wired characters in the middle of names,
etc.).  I can send you sample data if you are willing to take a look.  Even
though using 'read.delim' works, I am still curious what caused the problem
and potential problem that I may miss.

Thanks again,

SH




On Wed, Aug 21, 2013 at 10:58 AM, David Carlson <dcarlson@tamu.edu> wrote:

> This is not really enough information to diagnose the problem.
> What are the missing factor levels? Were the missing levels
> combined with another level or do you have missing values (NA)
> for those observations? Do the extra factor levels include
> embedded commas? There are differences between read.table and
> read.csv in the default quote= and comment.char= arguments.
>
> -------------------------------------
> David L Carlson
> Associate Professor of Anthropology
> Texas A&M University
> College Station, TX 77840-4352
>
> -----Original Message-----
> From: r-help-bounces@r-project.org
> [mailto:r-help-bounces@r-project.org] On Behalf Of SH
> Sent: Wednesday, August 21, 2013 9:36 AM
> To: r-help@r-project.org
> Subject: [R] data import: strange experience
>
> Dear List:
>
> I had some strange experience in importing data.  I wonder if
> anyone of you
> had the same problem before and would greatly appreciate your
> suggestion in
> advance.
>
> The original data set in excel format.
>
> Here is a brief summary of the procedure I did:
> 1. I saved the original excel data as csv and txt formats,
> separately.
> 2. I imported two data using the following codes.  There were no
> error
> messages.
> dftxt = read.table('df.txt',header=T, sep='\t')
> dfcsv = read.csv('df.csv',header=T, sep=',')
> 3. When I checked data with 'str', I found that factor levels of
> a variable
> were different each other.
> Levels of dftxt were less than those of dfcsv (48 vs 52).
> 4. So, I checked 'df.txt' file and found that the missing levels
> were still
> there, i.e., there is a no problem in text file.  I suspect that
> something
> happened when I imported it into R.
>
> Since there was no errors in importing the file into R, I do not
> have an
> idea where to start to fix it.  Do you have any suggestion?
>
> Thank you very much in advance,
>
> SH
>
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>
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