csv_monster.py

"""
Merge together .csv files. I'm creating this because I have 30 .csv files which need to be concatenated 
together. This uses the headers from 1 file and then will concate  w/o headers 1 through n such as :
    "customer-data.csv", "customer-data (1).csv" ... "customer-data (n).csv"
"""
# Todo: make use of the csv module and check headers from each file to make sure data lines up.
# Todo: allow explicit filenames to be passed in as well as lists of files
import csv

class CSV_Monster:

    current_filename = ""
    file_h = None
    i = None
    with_headers = False

    def __init__(self, base_name, last_i, first_i=None, save_name="final-csv-output.csv"):
        """
        Prepare to write the files. Open the save name and wait for run() to be called on the 
        utility 

        :base_name:str: The common file path and name of csv files to parse
        :last_i:int: The highest integer found in file names. such as base/name-csv-file (30).csv
        :first_i:int|None: My files start without a number so None is default.
        :save_name:str: The base name of the final output .csv
        """
        self.base_name = base_name
        self.save_name = save_name
        self.last_i = last_i
        self.i = first_i
        self.setup()

        # --- Open up the output file for writing
        print "Preparing to write to file: %s" % (self.save_name,)
        self.output_file = open(self.save_name, 'w+')


    def open(self, filename=None):
        """Open the self.current_filename for reading As of now this method is overkill,
        there is no way to explicitly tell the class to append a file which isn't named 
        using the self.base_name convention. But I would like to extend the object to 
        be able to allow the user to pass in specific names. 

        :filename:str: Pass filename to explicitly open. Default - self.current_filename
        :{return}:file_handler:
        """
        if filename is not None:
            self.current_filename = filename
        self.file_h = open(self.current_filename, 'r+')
        print "opening up file: %s" % (self.current_filename,)
        return self.file_h


    def next(self):
        """Setup the next file to be read then return file handler by calling self.open()
        #Todo: next() should be able to consume a list as well.
        :{return}:file_handler:
        """
        if self.i > self.last_i:
            return False

        self.current_filename = self.base_name
        if self.i is None:
            self.i = 0
            self.with_headers = True
        else:
            self.current_filename += " ("+str(self.i)+")"
            self.with_headers = False
        # complete the filenamme for the current file
        self.current_filename += ".csv"
        # incriment for the next file
        self.i = self.i + 1
        return self.open()


    def run(self):
        """Roll through each file and append lines to the output."""
        while self.next():
            # should skip the headers unless self.with_headers is True
            if not self.with_headers:
                self.file_h.next()
            # Append each line in current file to the output file
            for line in self.file_h:
                self.output_file.write(line)
            self.file_h.close()
        print "Closing the main file... completing operations."
        self.output_file.close()
        

    def check_headers(self):
        # TODO: Add header checks
        pass


# This will concate w/o headers customer-data.csv, customer-data (1).csv ... customer-data (30).csv
csv_monster = CSV_Monster("files/customer-data", 30)
csv_monster.run()