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| Original file line number | Diff line number | Diff line change |
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| --- | ||
| title: Huffman Encoding Algorithm | ||
| pubDatetime: 2023-12-10T22:30:00Z | ||
| featured: false | ||
| draft: false | ||
| tags: | ||
| - Greedy | ||
| - Algorithms | ||
| - Computer-Science | ||
| description: 허프만 알고리즘 | ||
| --- | ||
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| ## Table of contents | ||
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| ## `python` 코드 | ||
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| ```python | ||
| from __future__ import annotations | ||
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| import sys | ||
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| class Letter: | ||
| def __init__(self, letter: str, freq: int): | ||
| self.letter: str = letter | ||
| self.freq: int = freq | ||
| self.bitstring: dict[str, str] = {} | ||
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| def __repr__(self) -> str: | ||
| return f"{self.letter}:{self.freq}" | ||
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| class TreeNode: | ||
| def __init__(self, freq: int, left: Letter | TreeNode, right: Letter | TreeNode): | ||
| self.freq: int = freq | ||
| self.left: Letter | TreeNode = left | ||
| self.right: Letter | TreeNode = right | ||
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| def parse_file(file_path: str) -> list[Letter]: | ||
| chars: dict[str, int] = {} | ||
| with open(file_path) as f: | ||
| while True: | ||
| c = f.read(1) | ||
| if not c: | ||
| break | ||
| chars[c] = chars[c] + 1 if c in chars else 1 | ||
| return sorted((Letter(c, f) for c, f in chars.items()), key=lambda x: x.freq) | ||
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| def build_tree(letters: list[Letter]) -> Letter | TreeNode: | ||
| response: list[Letter | TreeNode] = letters # type: ignore | ||
| while len(response) > 1: | ||
| left = response.pop(0) | ||
| right = response.pop(0) | ||
| total_freq = left.freq + right.freq | ||
| node = TreeNode(total_freq, left, right) | ||
| response.append(node) | ||
| response.sort(key=lambda x: x.freq) | ||
| return response[0] | ||
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| def traverse_tree(root: Letter | TreeNode, bitstring: str) -> list[Letter]: | ||
| if isinstance(root, Letter): | ||
| root.bitstring[root.letter] = bitstring | ||
| return [root] | ||
| treenode: TreeNode = root | ||
| letters = [] | ||
| letters += traverse_tree(treenode.left, bitstring + "0") | ||
| letters += traverse_tree(treenode.right, bitstring + "1") | ||
| return letters | ||
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| def huffman(file_path: str) -> None: | ||
| letters_list = parse_file(file_path) | ||
| root = build_tree(letters_list) | ||
| letters = { | ||
| k: v for letter in traverse_tree(root, "") for k, v in letter.bitstring.items() | ||
| } | ||
| print(f"Huffman Coding of {file_path}: ") | ||
| with open(file_path) as f: | ||
| while True: | ||
| c = f.read(1) | ||
| if not c: | ||
| break | ||
| print(letters[c], end=" ") | ||
| print() | ||
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| if __name__ == "__main__": | ||
| huffman(sys.argv[1]) | ||
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| ``` | ||
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| ## How to Run | ||
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| python version: `3.11.6` | ||
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| ### Run `main.py` | ||
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| ``` | ||
| pip install pipenv | ||
| pipenv --python 3.11.6 | ||
| pipenv run python3 main.py input.txt | ||
| ``` | ||
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| ### Input | ||
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| `input.txt`: | ||
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| ``` | ||
| She Sells Seashells by the Seashore | ||
| ``` | ||
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| ### Output | ||
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| ```zsh | ||
| Huffman Coding of input.txt: | ||
| 001 010 111 110 001 111 011 011 100 110 001 111 0001 100 010 111 011 011 100 110 10100 10101 110 10110 010 111 110 001 111 0001 100 010 10111 0000 111 | ||
| ``` | ||
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| ## Execution Image | ||
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|  |