Improved CSV File merger/File splitter that I created to help with large amounts of .csv work I've been doing.

csv_monster.py

"""Created by Michael Rosata
Python 2.7

Merge together .csv files. I'm creating this because I have 30 .csv files which need to be concatenated.
I also have many files which need to be split, so I've added splitting functionality to this as well.
"""
import csv
import sys


class CSV_Monster:

    # current filename, file handle, index, whether to maintain headers when merging
    current_filename = ""
    file_h = None
    i = None
    with_headers = False

    def __init__(self, base_name, last_i, first_i=0, save_name="final-csv-output{}.csv", 
                 skips=set(), zero_index_name=None):
        """
        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: My files start without a number so 1 is default.
        :save_name str: The base name of the final output .csv if there is 1 singular file (merging)
        :skips set: A set of indexes which should be skipped
        :zero_index_name None|str: Pass in a starting name if there is a file to begin with which doesn't fit 
                                   convention in base_name
        """
        self.base_name = base_name
        self.save_name = save_name
        self.last_i = last_i
        self.i = first_i
        # --- Skips are file numbers which should be ignored for any reason .
        self.skips = skips
        self.zero_index_name = zero_index_name

        # --- Open up the output file for writing
        print("Preparing to write to file: {}".format(self.save_name.format('')))
        self.output_file = open(self.save_name.format(''), '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: {}".format(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 a generator I think.

        :{return} file_handler:
        """
        if self.i > self.last_i:
            return False
        # Check that this isn't a skip index
        if self.skips and len(self.skips):
            while self.i in self.skips:
                self.i += 1

        if self.zero_index_name is not None:
            self.current_filename = self.zero_index_name
            self.zero_index_name = None
            self.with_headers = True
        else:
            self.current_filename = self.base_name.format(self.i) 
            self.with_headers = False

        # incriment for the next file
        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... {}".format(self.save_name.format('')))
        self.output_file.close()
        

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


    def split(self, chunk_size=500):
        """Split the current file into files of row size n where n is chunk_size
        First use self.open() to open a file to read from and then call self.split()

        :chunk_size int: How many lines per file.
        """
        line_num = 0
        file_num = 1
        if self.file_h is None:
            # If no file_h Split assumes to split the base_name file.
            self.open(self.base_name)
        for line in self.file_h:
            line_num += 1
            if line_num == 1 or file_headers is None:
                file_headers = line
            if int(line_num) % int(chunk_size) == 1:
                if self.output_file is not None:
                    self.output_file.close()
                    del self.output_file
                next_filename = self.save_name.format(file_num)
                print("About to write next {0} lines into file: {1}".format(chunk_size, next_filename))
                self.output_file = open(next_filename, 'w+')
                file_num += 1
                # Write the file headers as the first line of each file
                self.output_file.write(file_headers)
                if line_num == 1:
                    # continue because we dont' want to write headers 2 times.
                    continue

            self.output_file.write(line)
        self.file_h.close()
        self.output_file.close()



if __name__ == '__main__':
    # Make split_mode True to split files (for examples).
    split_mode = False

    if split_mode is True: 
        # Splitting files example
        csv_monster = CSV_Monster("large-files/all-orders.csv", 1, save_name="orders-chunk-{}.csv")
        csv_monster.split(400)

    elif __name__ == '__main__' and split_mode is not True:
        # Merging files example
        csv_monster = CSV_Monster("split-files/orders-{}.csv", 34, first_i=1, save_name="orders-completed.csv", 
                                  skips=set((2, 9, 10, 22, 27, 28, 29, 33)))
        csv_monster.run()