Questions
Find answers to frequently asked development questions. For information about Better Stack products, explore our docs.
How to Check for Nan Values
In pandas, you can check for NaN (Not a Number) values using the isna() or isnull() methods. These methods return a DataFrame of the same shape as the original DataFrame, where each element is True...
How to Change the Order of Dataframe Columns?
To change the order of DataFrame columns in pandas, you can simply reassign the DataFrame with the desired column order. Here's how you can do it: Suppose you have a DataFrame named df: import pand...
What Is the Python 3 Equivalent of “Python -M Simplehttpserver”
The Python 3 equivalent of python -m SimpleHTTPServer is: python -m http.server In Python 3, the http.server module provides a simple HTTP server that serves files from the current directory and it...
How Do I Install Pip on Macos or OS X?
On macOS or OS X, pip is typically installed alongside Python. If you've installed Python using the official installer from python.org or via Homebrew, pip should already be available. Here's how y...
If/Else in a List Comprehension
You can use if/else statements in a list comprehension to conditionally include elements in the resulting list. The syntax for this is: Here's an example: List comprehension with if/else numbers = ...
How Do I Get the Filename without the Extension from a Path in Python?
You can get the filename without the extension from a path in Python using the os.path module. Here's how you can do it: import os File path file_path = '/path/to/file.txt' Get the filename without...
Why Do Python Classes Inherit Object?
In Python 2.x, it was not necessary to explicitly inherit from the object class when defining a new class. However, in Python 3.x, it is recommended to explicitly inherit from object for several re...
Save Plot to Image File Instead of Displaying It?
To save a plot to an image file instead of displaying it, you can use the savefig() function provided by the matplotlib.pyplot module. Here's how you can do it: import matplotlib.pyplot as plt Gene...
How to Use Relative Imports in Python?
Relative imports in Python are used to import modules relative to the current module's location in the package hierarchy. They are specified using dot notation to indicate the relative position of ...
How to Prettyprint a Json File in Python?
You can pretty print a JSON file in Python using the json module's loads() function to parse the JSON data, and then the json.dumps() function with the indent parameter to output it in a readable f...
How to Create Static Methods in Python?
In Python, a static method is a method that belongs to a class but does not operate on instances of that class. Unlike instance methods, static methods do not have access to the instance (self) or ...
How to Read a File Line-by-Line into a List?
You can read a file line-by-line into a list in Python using a loop to iterate over each line in the file and appending each line to a list. Here's how you can do it: Open the file for reading with...
How to Test a Single File Under Pytest
To run a single test file with pytest, use the command pytest followed by the file path: pytest tests/test_file.py To execute a specific test within that file, append :: and the test name to the fi...
How to Assert if an Exception Is Raised With Pytest?
Pytest can be used to test whether a function raises an exception. For instance, consider a division function that raises a ZeroDivisionError if there is an attempt to divide by zero: def divide(x,...
How to Use Pytest With Virtualenv?
To effectively use Pytest within a Python virtual environment, follow these instructions: First, create a virtual environment using Python. Assuming you are using the current latest version, (Pytho...
How to Skip Directories With Pytest?
You can instruct Pytest to exclude specific directories from testing with the --ignore option. To exclude a single directory, execute: pytest --ignore=somedirectory To exclude multiple directories ...
How to Solve the ModuleNotFoundError With Pytest?
To fix the ModuleNotFoundError in pytest, you can start by making your tests directory a Python package.This can be achieved by including an empty __init__.py file to the directory: └── tests/ ...
How to Profile and Identify Slow Tests?
You can easily profile the duration of tests using pytest to identify slow tests using the --durations=N option. To display the execution time of every test function, set --durations to 0: pytest -...
How to Disable a Test Using Pytest?
If you need to disable a specific test when running your test suite with pytest, use the pytest skip decorator. Suppose you have the following tests in your test suite: import pytest def test_addit...
How to Debug Pytest With pdb Breakpoints?
To debug a pytest test using pdb, you can manually insert a breakpoint by adding import pdb; pdb.set_trace() in your test: import pytest def divide(x, y): return x / y def testzerodivision(): ...
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