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Commit b486ac6

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om-ashish-soniMaximSmolskiycclausspre-commit-ci[bot]
authored
added coordinate_compression (#9317)
* added coordinate_compression algorithm * added coordinate_compression & doctest * adding return type hints and utilized enumerate * adding exmaple usage in main function * added type hints, for list and dict * updating DIRECTORY.md * Update other/coordinate_compression.py Co-authored-by: Christian Clauss <cclauss@me.com> * Update other/coordinate_compression.py Co-authored-by: Christian Clauss <cclauss@me.com> * Update other/coordinate_compression.py Co-authored-by: Christian Clauss <cclauss@me.com> * Update other/coordinate_compression.py Co-authored-by: Christian Clauss <cclauss@me.com> * Update other/coordinate_compression.py Co-authored-by: Christian Clauss <cclauss@me.com> * Update other/coordinate_compression.py Co-authored-by: Christian Clauss <cclauss@me.com> * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * Update other/coordinate_compression.py Co-authored-by: Christian Clauss <cclauss@me.com> * Update other/coordinate_compression.py Co-authored-by: Christian Clauss <cclauss@me.com> * Update coordinate_compression.py * Create coordinate_compression.py * updating DIRECTORY.md * Delete other/coordinate_compression.py * updating DIRECTORY.md * Update coordinate_compression.py * Update coordinate_compression.py * Update coordinate_compression.py * Update coordinate_compression.py * Update coordinate_compression.py * Update coordinate_compression.py * Update coordinate_compression.py * Update coordinate_compression.py * Update coordinate_compression.py --------- Co-authored-by: Maxim Smolskiy <mithridatus@mail.ru> Co-authored-by: MaximSmolskiy <MaximSmolskiy@users.noreply.github.com> Co-authored-by: Christian Clauss <cclauss@me.com> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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‎DIRECTORY.md

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## Data Compression
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* [Burrows Wheeler](data_compression/burrows_wheeler.py)
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* [Coordinate Compression](data_compression/coordinate_compression.py)
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* [Huffman](data_compression/huffman.py)
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* [Lempel Ziv](data_compression/lempel_ziv.py)
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* [Lempel Ziv Decompress](data_compression/lempel_ziv_decompress.py)
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"""
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Assumption:
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- The values to compress are assumed to be comparable,
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values can be sorted and compared with '<' and '>' operators.
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"""
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class CoordinateCompressor:
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"""
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A class for coordinate compression.
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This class allows you to compress and decompress a list of values.
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Mapping:
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In addition to compression and decompression, this class maintains a mapping
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between original values and their compressed counterparts using two data
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structures: a dictionary `coordinate_map` and a list `reverse_map`:
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- `coordinate_map`: A dictionary that maps original values to their compressed
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coordinates. Keys are original values, and values are compressed coordinates.
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- `reverse_map`: A list used for reverse mapping, where each index corresponds
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to a compressed coordinate, and the value at that index is the original value.
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Example of mapping:
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Original: 10, Compressed: 0
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Original: 52, Compressed: 1
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Original: 83, Compressed: 2
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Original: 100, Compressed: 3
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This mapping allows for efficient compression and decompression of values within
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the list.
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"""
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def __init__(self, arr: list[int | float | str]) -> None:
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"""
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Initialize the CoordinateCompressor with a list.
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Args:
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arr: The list of values to be compressed.
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>>> arr = [100, 10, 52, 83]
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>>> cc = CoordinateCompressor(arr)
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>>> cc.compress(100)
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3
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>>> cc.compress(52)
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1
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>>> cc.decompress(1)
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52
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"""
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# A dictionary to store compressed coordinates
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self.coordinate_map: dict[int | float | str, int] = {}
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# A list to store reverse mapping
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self.reverse_map: list[int | float | str] = [-1] * len(arr)
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self.arr = sorted(arr) # The input list
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self.n = len(arr) # The length of the input list
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self.compress_coordinates()
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def compress_coordinates(self) -> None:
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"""
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Compress the coordinates in the input list.
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>>> arr = [100, 10, 52, 83]
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>>> cc = CoordinateCompressor(arr)
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>>> cc.coordinate_map[83]
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2
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>>> cc.coordinate_map[80] # Value not in the original list
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Traceback (most recent call last):
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...
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KeyError: 80
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>>> cc.reverse_map[2]
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83
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"""
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key = 0
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for val in self.arr:
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if val not in self.coordinate_map:
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self.coordinate_map[val] = key
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self.reverse_map[key] = val
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key += 1
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def compress(self, original: float | str) -> int:
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"""
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Compress a single value.
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Args:
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original: The value to compress.
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Returns:
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The compressed integer, or -1 if not found in the original list.
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>>> arr = [100, 10, 52, 83]
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>>> cc = CoordinateCompressor(arr)
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>>> cc.compress(100)
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3
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>>> cc.compress(7) # Value not in the original list
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-1
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"""
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return self.coordinate_map.get(original, -1)
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def decompress(self, num: int) -> int | float | str:
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"""
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Decompress a single integer.
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Args:
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num: The compressed integer to decompress.
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Returns:
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The original value.
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>>> arr = [100, 10, 52, 83]
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>>> cc = CoordinateCompressor(arr)
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>>> cc.decompress(0)
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10
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>>> cc.decompress(5) # Compressed coordinate out of range
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-1
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"""
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return self.reverse_map[num] if 0 <= num < len(self.reverse_map) else -1
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if __name__ == "__main__":
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from doctest import testmod
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testmod()
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arr: list[int | float | str] = [100, 10, 52, 83]
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cc = CoordinateCompressor(arr)
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for original in arr:
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compressed = cc.compress(original)
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decompressed = cc.decompress(compressed)
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print(f"Original: {decompressed}, Compressed: {compressed}")

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