Python File Handling Basics

A file is a sequence of bytes stored on disk/permanent storage for related data.
File handling in Python supports file creation, updating, reading, and deletion.

Steps include:
- Opening a file.
- Performing operations (reading or writing).
- Closing the file.

Python supports three primary types of data files:
- Text files
- Binary files
- CSV files

Binary Files
- Efficient for large files.
- Contains data patterns without delimiters.
CSV Files
- Common and platform-independent format.
- Uses plain text with delimiters, readable by text editors.
- Ends each line automatically when delimiter is absent.

Methods to read data from text files include:
- read(): Reads specified bytes or entire file as a string.
- readline(): Reads a single line as a string; can limit bytes read.
- readlines(): Retrieves all lines as a list of string elements.
Note: ‘\n’ is treated as a two-byte special character.

Binary files store data in a non-text format, represented as sequences of 1s and 0s.
Data in binary files is processed byte by byte; they don't have delimiters or end-of-line (EOL) characters.
These files do not undergo conversions like text files, making them more efficient.
Binary files are faster to process and require less memory than text files.
Common extensions for binary files include .bin, .dat, etc.
The pickle module in Python provides dump and load functions for handling binary files.
When opening binary files in Python, 'b' must be included in the mode (e.g., 'rb' for reading).

The with statement simplifies file handling by automatically closing files after the block execution.
Syntax: with open(file_name, access_mode) as file_object:
It combines file opening, processing, and built-in exception handling.
Example: with open(“myfile.txt”, “r+”) as myObject: content = myObject.read()

A Comma Separated Values (CSV) file is a plain text file that organizes data with commas, facilitating data exchange between applications.
Commonly utilized for managing large data sets, CSV files can be generated by software such as spreadsheets (e.g., Excel) and databases (e.g., Oracle, MySQL).
CSV files allow easy import and export of data for storage or analysis.

A sample CSV file format may look like:

Name, DOB, City
Ram, 12-Jul-2001, Delhi
Mohan, 23-Jan-2005, Delhi

The CSV module is part of Python's Standard Library, enabling reading and writing of CSV formatted data.
To use, the CSV module must first be imported: import csv.
Key methods in the CSV module include:
- writer(): Creates a writer object to convert user data into delimited strings.
- reader(): Reads data from a CSV file.
The Writer object includes additional methods such as:
- writerow(): Writes a single row of data.
- writerows(): Writes multiple rows of data.