Python樹林– category –

When handling decimals in computers, using floating-point numbers (float) can cause errors because numbers like 1/3 become 0.3333... and cannot be represented exactly. If you want to maintain and calculate exact values as mathematical "f...

コンピュータで小数を扱う際、浮動小数点数（float）を使用すると、1 / 3 が 0.3333... となり、厳密な計算ができずに誤差が生じることがあります。 数学的な「分数（有理数）」として正確に値を保持・計算したい場合、Pythonの標準ライブラリである fract...

Python's standard round() function adopts "Round half to even" (Banker's rounding), so it may produce results different from the standard "rounding half up" method you learn in school. When you need fractional processing based on strict ...

Python標準の round() 関数は「偶数丸め（銀行丸め）」を採用しているため、一般的な「四捨五入」とは異なる結果になることがあります。 金融計算など、厳密なルールに基づいた端数処理が必要な場合は、標準ライブラリの decimal モジュールを使用します。...

Python's standard floating-point numbers (float type) represent values internally using binary. Therefore, even simple decimals like 0.1 cannot be represented accurately, causing minute "errors" during calculation. In scenarios requiring...

Pythonの標準的な浮動小数点数（float型）は、内部的に2進数で値を表現しているため、0.1 のような単純な小数であっても正確に表現できず、計算時に微細な「誤差」が発生することがあります。 金融計算や科学技術計算など、わずかな誤差も許されない厳密な...

Whether for physical simulations, statistical processing, or controlling character movement in game development, there are many situations where trigonometric functions (sine, cosine, tangent) are required in programming. Python's standa...

Logarithmic calculations are essential for data scaling, calculating information entropy, and implementing physics formulas. The Python standard library math module provides a general-purpose log() function, as well as log10() and log2()...

In fields such as scientific computing and machine learning, the exponential function y=ex, with the base e (Napier's number, approx. 2.718), appears frequently. The Python standard library math module provides the math.exp() function to...

When creating programs for scientific calculations or geometry, mathematical constants like Pi ($\pi$) and Euler's number ($e$) are frequently used. Python's standard math module allows you to use these constants with high precision. It ...

In programming, you often need to find the "quotient" (the answer to division) and the "remainder" (what is left over). Common examples include converting total seconds into "minutes and seconds" or calculating the leftovers when distrib...

In scientific and geometric calculations (such as area and volume), you often need to calculate the square, cube, or N-th power of a number. Python provides the ** operator and the built-in pow() function as standard methods for calculat...

In programming, you often need to round decimal numbers to a specific position or approximate large numbers (e.g., changing 12,345 to 12,000). Python provides the built-in round() function for this purpose. However, this function behaves...

When performing data analysis or numerical calculations, you often need to find basic metrics like absolute values, sums, maximums, and minimums to understand the "magnitude" or "trends" of your data. Python provides convenient built-in ...

When handling decimal numbers in computers, they are represented in binary internally, which inevitably causes minute "calculation errors." Therefore, comparing floating-point numbers (float) using the == operator may not yield the expec...

When displaying floating-point numbers (float) in Python using print(), they are usually automatically rounded to a readable length. However, in scientific computing or debugging, you may want to display more digits (or a specific number...

When performing numerical calculations in Python, type conversion (casting) between integers (int) and floating-point numbers (float) is a frequently used operation. For example, you might want to convert an integer to a decimal for calc...

In programming, you often need to convert decimal numbers into formats that computers interpret easily, such as binary, or formats used in memory dumps, such as hexadecimal. Python provides convenient built-in functions to convert number...

When handling numbers in Python programs, we usually use decimal numbers (0-9). However, depending on the application, it may be more intuitive to use binary, octal, or hexadecimal. For example, binary is suitable for bitwise operations,...

When outputting files, ensuring the destination directory (folder) exists beforehand is necessary. The Python standard library os module provides two functions for creating directories: os.mkdir() and os.makedirs(). os.makedirs() is part...

In file manipulation programs, deleting unnecessary temporary files or directories containing old data is often necessary. In Python, the function used differs depending on whether the target is a "file" or a "directory (folder)". This a...

Copying files or directories is essential when creating data backups or replicating template folders for new projects. The Python standard library shutil module (Shell Utilities) allows executing these operations with simple function cal...

In scenarios like organizing files, rotating logs, or processing backups, you often need to move files or directories to a different location. To do this in Python, using the move() function from the standard library shutil module is the...

In file manipulation programs, it is often necessary to branch processing based on file extensions. Common scenarios include "processing only image files (.jpg, .png)" or "excluding anything other than text files (.txt)". The Python stan...

In file manipulation programs, you often need to distinguish whether a specified path is a "file" or a "directory (folder)" to handle them differently. For example, after getting a list of items in a directory, you might want to perform ...

In file manipulation scripts, you often need to process all files inside a specific folder. There are two main ways to get a list of contents in a directory in Python: pathlib module (Recommended): An object-oriented, modern approach int...

Before performing file operations, checking "if the file is really there" is very important to prevent errors like FileNotFoundError. The Python standard library os.path module provides several functions to check for existence. You need ...

In programs that perform file operations, we use a "Path" to specify the file location. There are two types of paths: "Absolute Path," which describes the location from the root directory, and "Relative Path," which describes the locatio...

When reading or writing files in a Python script using relative paths (e.g., data.txt), the program searches for them based on the "Current Directory (Current Working Directory)." Therefore, knowing where your program is currently runnin...

In programs handling file paths, operations like "extracting just the filename from a full path" or "getting the parent directory path excluding the filename" are frequent. Python's standard library os.path module provides the split() fu...