Python File Handling Overview

The readline() method in Python reads a single line from a file object, including the newline character '\n'.

The readlines() method reads all lines from a file object and returns them as a list of strings, where each element in the list represents a single line, including the newline character '\n'.

When you are finished working with a file object, you should close it using the close() method to release the resources it was using. This is important for file integrity and efficiency.

By using a loop, you can iterate through each line in the file object and process it individually, enabling you to read and interpret the file line by line.

The 'r' mode in Python's open function indicates that the file is opened for reading data. This means you can only access the contents of the file and cannot modify it.

The open() function takes the file path and the access mode as arguments to create a file object. This object allows you to work with the file, such as reading or writing data.

You can open a file in Python using the built-in function open(). By passing the filename and the desired access mode as arguments, you create a file object that allows you to read or write data.

File handling in Python involves using the open() function to open a file and then reading the content using methods like readline() or readlines(). Finally, you close the file using the close() function to release resources.

Opening a file in Python involves using the "open()" function with the file name as an argument. This function returns a file object, enabling read or write operations. The default mode is "rt" which stands for reading a text file.

The "read()" method of a file object allows you to read the entire contents of a file. For example, "file.read()" reads the whole file and returns its content as a string.

If you only need a specific portion of a file, you can use the "read(n)" method with an integer 'n' specifying the number of characters you want to read. It retrieves the specified number of characters from the file.

The "readline()" method reads one line at a time from a file. It returns the line as a string, including the newline character at the end.

The file path specifies the location of a file on your computer's file system. It's required when the file you want to access is not in the same directory as your Python script.

The default mode for opening a file is "rt" which stands for "read text". This indicates that we want to read text data from the file.

If the file you are attempting to access doesn't exist in the specified location, Python will raise a "FileNotFoundError". This error message indicates that the file you're trying to access was not found.

The file object, accessed through the "open()" function, provides the interface for interacting with the file. It has methods such as "read()", "readline()", and "write()" which allow you to perform operations on the file content.

The csv.DictWriter function is used to write data from dictionaries into a CSV file. It allows you to organize data into columns based on dictionary keys. This can be useful for storing structured data in a tabular format.

The writeheader() method writes a header row to the CSV file. The header row includes the names (keys) of the columns specified in the fieldnames argument.

The writerows() method iterates through a list of dictionaries and writes each dictionary as a separate row in the CSV file.

The "r+" mode opens a file for both reading and writing. This allows you to modify existing content or append new data to the file.

The "w" mode opens a file for writing only. If the file exists, it is overwritten with new content.

The open() function opens a specified file in the specified mode. If no mode is specified, it defaults to the "r" mode for reading the file.

The readlines() method reads all lines of a file and returns a list of strings, where each string represents a line in the file.

The with open('filename.txt', 'r') as file: statement opens a file in read mode ('r') and automatically closes it when the code block ends.

The file.read() method reads all content from the file and returns it as a single string.

The try...except... block is used to handle exceptions, such as the FileNotFoundError. The try block contains the code that might raise an exception, and the except block catches it and provides a response.

The file.write('some text') method writes a string to the file. It can append or overwrite existing content, depending on the file opening mode.

The 'a' mode in open('filename.txt', 'a') appends the new content to the end of the existing file without overwriting it.

The os.remove('filename.txt') function removes the file permanently from the file system.

CSV (Comma-Separated Values) is a plain text format used for storing tabular data. Each line of the file represents a row, and each field (column value) is separated by a comma.

A code block designed to handle potential errors during file operations, effectively preventing program crashes. It uses 'try', 'except', and 'finally' blocks to manage exceptions.

An exception raised when a file specified in a code block cannot be found. It's triggered if the file doesn't exist in the expected location.

An exception thrown when the program lacks the necessary permissions to access or modify a file. This may occur due to security restrictions or user privileges.

A concise syntax in Python that provides a structured way to manage files with a focus on safety and efficiency. The 'with' statement automatically closes the file after the code block executes, preventing resource leaks.

A core concept in programming that involves handling potential errors gracefully, ensuring that program execution is not interrupted. Exceptions are events that cause unexpected program behavior, and exception handling allows for clean recovery and error reporting.

The process of creating a new file on the computer system and writing data into it, like writing a story in a brand-new book. This involves specifying the file name and the write mode ('w') to overwrite existing content or create a blank file.

A fundamental operation in file handling that involves reading data from a file, much like reading words from a book. This process extracts the content of the file and allows you to manipulate or display the data.

A useful feature that allows you to navigate and perform operations on directories and files, like navigating a file system on your computer.

The csv.reader() function processes a CSV file and returns each row as a list. Each element in the list represents a cell in the CSV row.

The open('file.csv', 'r') part opens the file in read mode, allowing you to access the file contents for processing.

The for row in reader: loop iterates over each row in the CSV file, processing each row as a list.

Use next(reader) to skip the first row, typically the header row, before processing the rest of the data using a loop.

The csv.DictReader() function reads the CSV file and returns each row as a dictionary. The keys of the dictionary are taken from the header row.

The with open('file.csv', 'r') as file: line opens the file for reading. Inside the with block, you create a csv.DictReader object called reader. The loop iterates over each row in the CSV file, and row is a dictionary representing each row.

After reading each row as a dictionary, you can access the specific column information using the column name as the key.

Using csv.DictReader() makes your code more readable because you can access specific column information directly by using the column names instead of relying on indices.