new: python news

- magic methods
- count occurrences of elements with Counter
- Throwaway variables

content/Programming/Python Notes.md

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+---
+Author:
+  - Xinyang YU
+Author Profile:
+  - https://linkedin.com/in/xinyang-yu
+tags:
+  - python
+Creation Date: 2024-12-15, 20:06
+Last Date: 2024-12-15T20:55:07+08:00
+References: 
+draft: 
+description: 
+---
+## Magic Methods
+---
+
+| Method     | Purpose                                                      | Example Usage             |
+| ---------- | ------------------------------------------------------------ | ------------------------- |
+| `__init__` | Initializes object attributes during instantiation.          | `p = Person("Alice", 25)` |
+| `__lt__`   | Defines behavior for `<` operator for custom objects.        | `print(n1 < n2)`          |
+| `__str__`  | Returns a human-readable string representation of an object. | `print(p)` or `str(p)`    |
+
+- **Methods starting and ending with double underscores**. They are defined by built-in classes in Python and commonly used for operator overloading
+- For more examples, see [docs](https://www.geeksforgeeks.org/dunder-magic-methods-python/)
+
+## Count Occurrences of Elements
+---
+```python
+from collections import Counter
+
+# Count characters in a string
+Counter("banana")
+# Output: Counter({'a': 3, 'n': 2, 'b': 1})
+
+# Count characters in a string
+Counter([1, 2, 2, 3, 3, 3])
+# Output: Counter({3: 3, 2: 2, 1: 1})
+
+# Most Common Elements
+Counter([1,1,1,2,2,3,4,5,6]).most_common(2)
+# Output: [(1, 3), (2, 2)]
+```
+
+
+## Throwaway Variable
+---
+```python
+for _ in range(k):
+	print("This will print k times")
+```
+
+- `_` is the throwaway variable. This is a way to indicate to other developers that the loop variable is intentionally not going to be used.