![]() The argparse Python library Figure 1: My terminal screen is used to run a Python script with command line arguments.įirst, let’s make a new script, naming it simple_example.py : # import the necessary packages I’ll also be showing how P圜harm users can run a script without ever leaving P圜harm if they so choose. In the remainder of today’s post we will learn about the Python argparse package via two script examples. In the case of deep learning, for which this blog is also known, you’ll see model paths or epoch counts as command line arguments. Given that this is computer vision and image processing blog, a lot of the arguments you’ll see here are image paths or video paths. ![]() If you know how functions are declared and called in various programming languages, then you’ll immediately feel at home when you discover how to use command line arguments. You can draw the analogy that a command line argument is similar to a function parameter. This allows us to give our program different input on the fly without changing the code. Why do we use command line arguments?Īs stated, command line arguments give additional information to a program at runtime. That being said, on this blog we make extensive use of command line arguments in our Python scripts and I’d even go so far to say that 98% of the articles on this blog make use of them. Not all programs have command line arguments as not all programs need them. They contain additional information for our program so that it can execute. What are command line arguments?Ĭommand line arguments are flags given to a program/script at runtime. And by the end of the post you’ll be able to work with command line arguments like a pro. You’ll find that you do not have to modify a single line of code to work with them. Inside the rest of today’s post you’ll learn that command line arguments are a lot easier to work with than they seem (even if you have never used them before). Many other readers run into similar problems when working with command line arguments - but the honest truth is that nearly all of these errors can be avoided by taking the time to educate yourself on command line arguments. Usage: detect_faces.py -i IMAGE -p PROTOTXT -m MODEL ĭetect_faces.py: error: the following arguments are required: -i/–image, -p/–prototxt, -m/–modelĪrjun is far from alone in struggling with this error. Hey Adrian, I just downloaded the source code to your deep learning face detection blog post, but when I execute it I get the following error: In fact, just an hour before I decided to write this blog post, I received the following email from Arjun: Shortcuts to comment multiple lines in Python and most popular IDEsįor commenting several lines in most popular IDEs you can use next shortcuts.Looking for the source code to this post? Jump Right To The Downloads Section Python, argparse, and command line argumentsĮach day I receive 3-5 emails or comments from PyImageSearch readers who are struggling with command line arguments. The example image below multiline commend and docstring: Many projects and organizations are using this kind of comments when they want to have good documentation. ![]() Here you can find an example for such: def complex(real=0.0, imag=0.0): Multiline docstrings exampleĭescriptive multiline docstrings help for understanding and maintaining the code. Note 2: For one liners it is recommended the quotes to be on the same line as the comment. Note 1: Even if a docstring contains only one line, triple quotes should be used because it's easier to expand it in future. What is a docstring? The first statement in a class, method, function or module definition which is a string is called a docstring. Unless used as docstrings, they generate no code! :-)Īccording to this tip you can do comments in this way: """line1 Guido van Rossum (the Python creator, Python BDFL) tweeted once a "pro tip" for Python multiline Python tip: You can use multi-line strings as multi-line comments. This is the default comment for most popular Python IDEs like P圜harm, Sublime, VS code. ![]() Python multiline comment would look like to: # This Some languages like Java have native support for multiline comments. In Python there is a special symbol for comments which is #. How to comment out multiple lines in Python Multiline comment is created simply by placing them inside triple-quoted strings: '''/ """ and '''/ """.īoth examples have valid syntax in Python. Multiline comments in Python can start with ''' and end with '''. PEP 8 and bigger part of the community prefers to comment out like: # This is a comment One option is to add # at the start of each line. Python has several ways to comment multiple lines in Python.
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