title: File Iteration Returns No Data in files
body: <p>My Script below is supposed to iterate through files located in this folder, with the ending csv. It reaches each file, but deletes all the data, instead of turning the 'NA' to 0. </p>
  
  <pre><code>import csv
  import os
  import sys 
  
  #file location
  folderpath = (r'\\Deturbansci19\cvi2$\ClientServices\CC&amp;A\Current\SSO\BRD Work\Parts Opportunity\Sample data')
  #print (folderpath)
  
  for root,dirs,files in os.walk(folderpath, topdown = False):
      for name in files:
          if 'Archive' not in root and name.endswith ('.csv'):
              f = os.path.join(r'\\Deturbansci19\cvi2$\ClientServices\CC&amp;A\Current\SSO\BRD Work\Parts Opportunity\Sample data\\'+name)
              #print (os.path.join(root, name))
              newfile = (r'\\Deturbansci19\cvi2$\ClientServices\CC&amp;A\Current\SSO\BRD Work\Parts Opportunity\Sample data\\'+name)
              with open(f, 'rb') as csvfile, open(newfile,'w',newline='') as newcsvfile:
                  csv_reader = csv.reader(csvfile, delimiter = ',')
                  csv_writer = csv.writer(newcsvfile, delimiter=',')
  
                  for lines in csv_reader:
                      #Replacing lines
                      replaced = lines[7].replace('NA', '0')
                      lines[7] = replaced
                      replaced = lines[8].replace('NA', '0')
                      lines[8] = replaced
                      replaced = lines[17].replace('NA', '0')
                      lines[17] = replaced
                      replaced = lines[18].replace('NA', '0')
                      lines[18] = replaced
                      replaced = lines[19].replace('NA', '0')
                      lines[19] = replaced
                      replaced = lines[20].replace('NA', '0')
                      lines[20] = replaced
                      replaced = lines[21].replace('NA', '0')
                      lines[21] = replaced
                      replaced = lines[22].replace('NA', '0')
                      lines[22] = replaced
                      replaced = lines[23].replace('NA', '0')
                      lines[23] = replaced
                      replaced = lines[24].replace('NA', '0')
                      lines[24] = replaced
                      replaced = lines[25].replace('NA', '0')
                      lines[25] = replaced
                      replaced = lines[26].replace('NA', '0')
                      lines[26] = replaced
                      replaced = lines[27].replace('NA', '0')
                      lines[27] = replaced
                      replaced = lines[28].replace('NA', '0')
                      lines[28] = replaced
                      replaced = lines[29].replace('NA', '0')
                      lines[29] = replaced
                      replaced = lines[30].replace('NA', '0')
                      lines[30] = replaced
                      replaced = lines[31].replace('NA', '0')
                      lines[31] = replaced
                      replaced = lines[32].replace('NA', '0')
                      lines[32] = replaced
                      replaced = lines[33].replace('NA', '0')
                      lines[33] = replaced
                      replaced = lines[34].replace('NA', '0')
                      lines[34] = replaced
                      replaced = lines[35].replace('NA', '0')
                      lines[35] = replaced
                      replaced = lines[36].replace('NA', '0')
                      lines[36] = replaced
                      replaced = lines[37].replace('NA', '0')
                      lines[37] = replaced
                      replaced = lines[38].replace('NA', '0')
                      lines[38] = replaced
                      replaced = lines[39].replace('NA', '0')
                      lines[39] = replaced
                      replaced = lines[40].replace('NA', '0')
                      lines[40] = replaced
                      replaced = lines[41].replace('NA', '0')
                      lines[41] = replaced
                      replaced = lines[42].replace('NA', '0')
                      lines[42] = replaced
                      replaced = lines[43].replace('NA', '0')
                      lines[43] = replaced
                      replaced = lines[44].replace('NA', '0')
                      lines[44] = replaced
                      replaced = lines[45].replace('NA', '0')
                      lines[45] = replaced
                      replaced = lines[46].replace('NA', '0')
                      lines[46] = replaced
                      replaced = lines[47].replace('NA', '0')
                      lines[47] = replaced
                      replaced = lines[48].replace('NA', '0')
                      lines[48] = replaced
                      replaced = lines[49].replace('NA', '0')
                      lines[49] = replaced
                      replaced = lines[50].replace('NA', '0')
                      lines[50] = replaced
                      replaced = lines[51].replace('NA', '0')
                      lines[51] = replaced
                     #Testing Purposes
                     #print (replaced)
                     #replaced = lines[0:50].replace('NA', '0')
                     #lines[0:50] = replaced
                     csv_writer.writerow(lines)
  </code></pre>