Seperating CSV rows into new, seperate files

TonyB anthonybol2 at
Sun Aug 15 22:45:15 CEST 2004

With some off post help I was able to come up with this little ditty
of a script but it still has one more problem.  When I run the script
it creates new files for each specific class.  While talking through
the logic with a friend, I realized that the gradebook software that
will import the list will ignore duplicate rows.  Not the best
solution but I need it to work this week.  In any case, it appears
that the new files have some sort of additional line terminator that
creates a blank row in the outputted file making the importing of the
list impossible.   This is based on the fact that when I try to open
the new files in MS Excel, they have blank rows after each row of
data.   If I open them in a text editor such as Notepad, they look
identical to the source file (which can be imported to the gradbook

Is there a way to SEE the newline terminators?
How can I use the csv.writer() to make sure there are no extra lines?

My Script:
import csv


# Open the input file and read the file to memory (may be too big a
file? ~ 2MB?).
reader = csv.reader(file("sample.csv"))

def createFilename(teacher,title,number,section):
   We need to remove spaces from the fields for better formatting of
the file name
   import re
   regex = re.compile('[^.A-Za-z0-9-_]')
   filename = '%s_%s_%s_section%s.txt' % (teacher, title, number,
   return regex.sub('_', filename)

for row in reader:
   filename = createFilename(row[TEACHER_NAME], row[COURSE_TITLE],

   fileobj = file(filename, 'a')
   newfile = csv.writer(fileobj)

Thanks to those who have helped!

Maik Röder <roeder at> wrote in message news:<mailman.1653.1092491778.5135.python-list at>...
> Hi TobyB,
> > Hi,
> > I've searched the group and need more information and guidance on this
> > issue I need to resolve next week. I work for the local school system
> > and I am working on a way to parse a CSV file of class lists from MS
> > Excel.  It is a ~2MB file with all teachers and all their classes in
> > it.  I thought I would use Python to do this since many people I know
> > tell me how great it is. 
> Pyhton is a good choice for treating texts.
> > The real sticking point is there are
> > duplicates of each teacher's classes embedded in the file (don't ask
> > why).  I want to break up the source file into the seperate class
> > files without duplication and use the teachers name, coursecode and
> > section in the filename.
> > 
> > Example Data:
> > Last Name	First Name	Grade	Period	Teacher Name	
> > SMITH           JOHN	         8      1	JONES	SALLY
> > 
> > Student ID		Course Code	Course Title	
> > 12345678	        1234	         ALGEBRA I
> > 
> > Course Section	Session
> > 1	        0
> > 
> > 
> > The course code and section number are the same in the duplicate
> > classes.  The difference is that the session number changes.   I'm
> > thinking that I will need to somehow iterate through the lines and
> > break the class when the course code changes and/or section change
> > (course codes can be the same but section numbers change with each
> > class).  Then I have to monitor the session number to see if there is
> > a duplicate course code and section but a different session number
> > would indicate that the class is a duplicate. Essentially, the session
> > number will be 0, 1, or 2 for a total of three lists of the same
> > class. Hopefully that makes sense.  Again don't ask why the data is
> > like this.
> > 
> > My humble attempts have not been very successful.  I've been trying
> > the csv modules to read the file but I am not sure how to procede
> > after that.
> > 
> > Any guidance is greatly appreciated.
> Use Python lists and dictionaries.
> Best regards,
> Maik Röder

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