Points to remember

Computer Science : Database concepts and MySql : Python and CSV Files

Points to remember:

·        A CSV file is a human readable text file where each line has a number of fields, separated by commas or some other delimiter

·        Excel is a binary file whereas CSV format is a plain text format

·        The two ways to read a CSV file are using csv.reader() function and using DictReader class.

·        The default mode of csv file in reading and writing is text mode

·        Binary mode can be be used when dealing with non-text files like image or exe files.

·        Python has a garbage collector to clean up unreferenced objects

·        close() method will free up the resources that were tied with the file

·        By default CSV files should open automatically in Excel

·        The CSV library contains objects and other code to read, write, and process data from and to CSV files.

·        “skipinitialspace” is used for removing whitespaces after the delimiter

·        To sort by more than one column operator.itemgetter() can be used

·        DictReader() class of csv module creates an object which maps data to a dictionary

·        CSV file having custom delimiter is read with the help of csv.register_dialect().

·        To sort by more than one column itemgetter() with multiple indices is used.

·        csv.reader and csv.writer work with list/tuple, while csv.DictReader and csv.DictWriter work with dictionary .

·        csv.DictReader and csv.DictWriter take additional argument fieldnames that are used as dictionary keys.

·        The function dict() is used to print the data in dictionary format without order.

·        The csv.writer() method returns a writer object which converts the user’s data into delimited strings.

·        The writerow() method writes one row at a time. Writerows() method is used to write all the data at once

·        Adding a new row at the end of the file is called appending a row.