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How-to articles, tricks, and solutions about PYTHON

Alternatives for returning multiple values from a Python function

Using a tuple:

python return-value return coding-style

Append integer to beginning of list in Python

To append an integer to the beginning of a list in Python, you can use the insert() method.

list python prepend

Argparse optional positional arguments?

In Python, the argparse module can be used to specify optional positional arguments by setting the nargs parameter to '?'.

python argparse

Asking the user for input until they give a valid response

To ask the user for input and repeat the prompt until they give a valid response, you can use a while loop and use a try-except block to catch any errors that may occur when trying to convert the user input to the desired data type.

validation input python

Automatically create requirements.txt

You can use the pip freeze command to automatically generate a requirements.txt file in Python.

python dependencies python-import requirements.txt

Behaviour of increment and decrement operators in Python

In Python, the increment operator (++) and decrement operator (--) do not exist.

python operators increment decrement

Best way to convert string to bytes in Python 3?

In Python 3, you can convert a string to bytes using the bytes function.

string python character-encoding python-3.x

Best way to strip punctuation from a string

One way to strip punctuation from a string is to use the str.translate() method in combination with the string.punctuation constant.

string python punctuation

Calling a function of a module by using its name (a string)

To call a function from a module by using its name as a string, you can use the importlib module.

object python reflection

Cannot find module cv2 when using OpenCV

The error message "Cannot find module cv2" usually indicates that the OpenCV library is not installed on your system, or that Python is unable to find the library.

python opencv python-2.7 raspberry-pi