Pythonic upload of CSV files in SQL from a directory, error with path

Question

Currently, my script downloads .txt files from an FTP site into a local directory (after checking to see if the directory already contains the file), converts each file into (separate) .csv. I need the data to port into a mysql database.

Here's the part that I'm having trouble with: running the second part of the script (ballotreader), where rows from the file are imported into SQL, when the path is not dynamic (i.e. R:\path\filename), the script works and the sql table populates. When the path is dynamic, (i.e. 'R:\path\'+filename) nothing populates. Any suggestions?

for filename in filenames:
    local_filename = os.path.join('R:\\path', filename)
    if os.path.isfile(local_filename) is False:
        print 'New file found.'
        file = open(local_filename, 'wb')
        ftp.retrbinary("RETR " + filename, file.write, 8*1024)
        file.close()
        print 'Downloaded '+filename+' file'
        txt_file = r""+filename
        csv_file = r""+filename+".csv" 
        in_txt = csv.reader(open(txt_file, "rb" ),delimiter = '|')
        outcsv = csv.writer(open(csv_file,'wb'))
        outcsv.writerows(in_txt)

        with open("R:\\path"+csv_file,'rb') as csv_input:
            ballotreader = csv.reader(csv_input, delimiter=',',quotechar ='|') 
            for row in ballotreader:  
                cursor = db.cursor()  
                if row[1] > 0:  

Answer 1

The problem is probably with the way you construct path. Try using os.path.join:

import os

path = os.path.join("R:\\path",csv_file)
with open(path,'rb') as csv_input:
...

Answer 2

Thanks @btel. That's the solution to my problem. My final code:

    with open(csv_file,'wb') as outcsv:
        out = csv.writer(outcsv, delimiter = '|')
        out.writerows(in_txt)