MurrayData opened a new issue, #38842:
URL: https://github.com/apache/arrow/issues/38842

   ### Describe the enhancement requested
   
   I have a problem with a regaulr data source in that it often contains 
embedded commas, but fields are not quoted.
   
   I have a workaround for this, using string manipulation to correct it, then 
io.BytesIO to pass the corrected data to pyarrow.csv.read_csv
   
   ````
   tables = []
   schema = pa.schema({c:'str' for c in columns})
   print(schema)
   convert_options = pa.csv.ConvertOptions(column_types=schema)
   nfixed = 0
   
   for f in files:
       
       lines = ','.join(columns)+'\n'
       with open(f) as infile:
           for line in infile:
               if line.count(',') > 15:
                   index = -1
                   for i in range(5):
                       index = line.find(',', index+1)
                   nfixed += 1
                   #print(f'Fixed {line} {line.count(",")} {index} 
{line[index]}')
                   line = line[:index] + ' ' + line[index+1:]
               lines += line
                   
       print('File', f)
       table_file = io.BytesIO(bytes(lines, encoding='utf8'))
       table = pa.csv.read_csv(table_file, convert_options=convert_options)
       print(table.shape)
       tables += [table]
       
   print(f'Fixed: {nfixed}')
   ````
   
   It would be good if invalid_row_handler is allowed to return a tuple 
containing the fixed version of the row to include in the table, for example:
   
   ````
   def row_handler(row):
       new_row = row[:4]
       new_row[5] = f'{row[4]} {row[5]}'.strip()
       new_row[6:] = row[7:]
       return new_row
   ````
   
   ### Component(s)
   
   Python


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