Argparse

Argparse⚑

Introduction to argparse in Python⚑

argparse is a powerful module in Python that provides a convenient way to parse command-line arguments and options. It simplifies the process of building command-line interfaces (CLIs) for your Python scripts or applications. In this tutorial, we will explore the basics of argparse and learn how to use it effectively.

Installation of argparse⚑

argparse is included in the Python standard library, so there is no need for additional installation.

Getting Started⚑

To start using argparse, you need to import the module:

import argparse

Creating a Parser⚑

The first step in using argparse is to create an ArgumentParser object, which will handle the parsing of command-line arguments. You can create a parser by invoking the argparse.ArgumentParser() constructor:

parser = argparse.ArgumentParser()

Adding Arguments⚑

Once you have a parser, you can add arguments to it. An argument is defined by invoking the add_argument() method on the parser object. Here\'s an example that adds a positional argument:

parser.add_argument('filename', help='name of the file to process')

In the example above, we added a positional argument called filename that represents the name of the file to be processed. The help parameter provides a description of the argument, which is displayed when the user requests help information.

You can also add optional arguments using the add_argument() method. Here's an example that adds an optional argument called --verbose:

parser.add_argument(
    '--verbose', action='store_true', help='increase output verbosity'
    )

In the example above, we added a positional argument called filename that represents the name of the file to be processed. The help parameter provides a description of the argument, which is displayed when the user requests help information.

Parsing Arguments⚑

After you have added the desired arguments, you need to parse the command-line arguments provided by the user. This is done by invoking the parse_args() method on the parser object:

args = parser.parse_args()

The parse_args() method returns an object containing the values of the parsed arguments. You can access the values by using dot notation on the args object. For example, to access the value of the filename argument:

print(args.filename)

Putting It All Together⚑

Here's an example that combines the concepts discussed above:

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('filename', help='name of the file to process')
parser.add_argument('--verbose', action='store_true', help='increase output verbosity')

args = parser.parse_args()

print('Processing file:', args.filename)
if args.verbose:
    print('Verbose mode enabled.')

ssuming this script is saved as script.py, you can run it from the command line as follows:

python script.py myfile.txt

If you include the --verbose flag:

python script.py myfile.txt --verbose

Example script of argparse⚑

import argparse

def greet_user(name, age=None, greeting='Hello', uppercase=False):
    # Modify greeting based on options
    if uppercase:
        greeting = greeting.upper()

    # Greet the user
    output = f'{greeting}, {name}!'
    if age:
        output += f' You are {age} years old.'

    return output

if __name__ == '__main__':
    # Create a parser
    parser = argparse.ArgumentParser(description='Script to greet a user')

    # Add arguments
    parser.add_argument('name', help='name of the user')  # positional argument
    parser.add_argument('--age', type=int, help='age of the user')  # optional argument with type validation
    parser.add_argument('--greeting', choices=['Hello', 'Hi', 'Hola'], default='Hello',
                        help='choose a greeting from the given options')  # optional argument with choices and default value
    parser.add_argument('--uppercase', action='store_true', help='convert greeting to uppercase')  # optional argument with flag

    # Parse the arguments
    args = parser.parse_args()

    # Call the greet_user function with the provided arguments
    output = greet_user(args.name, args.age, args.greeting, args.uppercase)

    # Print the greeting
    print(output)

Clarifications: * When an argument has a action, by default is False until you put it in the call to enable it, in this case it is --sortargument.