Python File I/O, CSV Handling, and Data Serialization Tutorial

This article provides a comprehensive guide to file operations in Python, covering the built‑in open() function, file handles, encoding, and mode options.

It explains absolute and relative paths, three ways to write path strings, and the advantages of using with open() for automatic resource management.

Common file access modes are listed ( r , w , a , binary modes rb , wb , ab , and combined modes r+ , w+ , a+ ), along with examples of reading the whole file, reading a specific number of characters, readline() , readlines() , and iterating over lines.

Pointer positioning methods tell() and seek(offset, whence) are demonstrated with examples.

A file‑copy utility is presented using os.path and binary reads/writes in a loop.

CSV handling is described: the format, writing with csv.writer (both writerow and writerows ), and reading with csv.reader .

In‑memory streams are introduced via StringIO for text and BytesIO for binary data, showing how to write and retrieve contents.

Standard I/O redirection using the sys module is shown for stdin , stdout , and stderr , including examples of capturing user input and redirecting output to files.

Data serialization concepts are explained, contrasting JSON (text‑based) and pickle (binary). Examples illustrate json.dumps , json.dump , json.loads , json.load , as well as pickle.dumps , pickle.dump , pickle.loads , and pickle.load , with notes on custom object encoding.

The differences between JSON and pickle are summarized, highlighting portability, supported data types, and use‑case considerations.