Compression/ppma by Nert53 · Pull Request #14810 · TheAlgorithms/Python

Nert53 · 2026-06-17T09:58:00Z

Describe your change:

Add an algorithm?
Fix a bug or typo in an existing algorithm?
Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
Documentation change?

Checklist:

algorithms-keeper

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Repository:

Contributing guidelines

Project Euler solution guidelines

Python:

Formatted string literals (f-strings)

Type hints

doctest

unittest

pytest

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algorithms-keeper · 2026-06-17T09:58:50Z

+    Core class for PPM compression algorithm containing compression and decompression.
+    """
+
+    def __init__(self, max_order: int = 2, alphabet_size: int = 256):


Please provide return type hint for the function: __init__. If the function does not return a value, please provide the type hint as: def function() -> None:

algorithms-keeper · 2026-06-17T09:58:50Z

+            defaultdict(lambda: defaultdict(int)) for _ in range(max_order + 1)
+        ]
+
+    def encode_text(self, text: str) -> dict:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function encode_text

algorithms-keeper · 2026-06-17T09:58:50Z

+
+        return {"readable_output": output, "ranges": output_ranges}
+
+    def decode_text(self, ranges: list) -> str:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function decode_text

algorithms-keeper · 2026-06-17T09:58:50Z

+
+        return decoded_text
+
+    def _get_context_probs(self, order: int, context: str) -> tuple[dict, int]:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function _get_context_probs

algorithms-keeper · 2026-06-17T09:58:50Z

+
+        return dict(counts), total_count
+
+    def process_char(self, char: str) -> tuple:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function process_char

algorithms-keeper · 2026-06-17T09:58:51Z

+
+        return output, output_ranges
+
+    def _update_models(self, char: str) -> None:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function _update_models

algorithms-keeper · 2026-06-17T09:58:51Z

+            (self.history + char)[-self.max_order :] if self.max_order > 0 else ""
+        )
+
+    def __reset_memory(self) -> None:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function __reset_memory

algorithms-keeper · 2026-06-17T09:58:51Z

+            defaultdict(lambda: defaultdict(int)) for _ in range(self.max_order + 1)
+        ]
+
+    def __str__(self) -> str:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function __str__

algorithms-keeper

Click here to look at the relevant links ⬇️

🔗 Relevant Links

Repository:

Contributing guidelines

Project Euler solution guidelines

Python:

Formatted string literals (f-strings)

Type hints

doctest

unittest

pytest

Automated review generated by algorithms-keeper. If there's any problem regarding this review, please open an issue about it.

algorithms-keeper commands and options

algorithms-keeper actions can be triggered by commenting on this PR:

@algorithms-keeper review to trigger the checks for only added pull request files

@algorithms-keeper review-all to trigger the checks for all the pull request files, including the modified files. As we cannot post review comments on lines not part of the diff, this command will post all the messages in one comment.

NOTE: Commands are in beta and so this feature is restricted only to a member or owner of the organization.

algorithms-keeper · 2026-06-17T10:01:11Z

+            defaultdict(lambda: defaultdict(int)) for _ in range(max_order + 1)
+        ]
+
+    def encode_text(self, text: str) -> dict:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function encode_text

algorithms-keeper · 2026-06-17T10:01:11Z

+
+        return {"readable_output": output, "ranges": output_ranges}
+
+    def decode_text(self, ranges: list) -> str:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function decode_text

algorithms-keeper · 2026-06-17T10:01:11Z

+
+        return decoded_text
+
+    def _get_context_probs(self, order: int, context: str) -> tuple[dict, int]:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function _get_context_probs

algorithms-keeper · 2026-06-17T10:01:11Z

+
+        return dict(counts), total_count
+
+    def process_char(self, char: str) -> tuple:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function process_char

algorithms-keeper · 2026-06-17T10:01:11Z

+
+        return output, output_ranges
+
+    def _update_models(self, char: str) -> None:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function _update_models

algorithms-keeper · 2026-06-17T10:01:11Z

+            (self.history + char)[-self.max_order :] if self.max_order > 0 else ""
+        )
+
+    def __reset_memory(self) -> None:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function __reset_memory

algorithms-keeper · 2026-06-17T10:01:11Z

+            defaultdict(lambda: defaultdict(int)) for _ in range(self.max_order + 1)
+        ]
+
+    def __str__(self) -> str:


As there is no test file in this pull request nor any test function or class in the file data_compression/ppma.py, please provide doctest for the function __str__

Nert53 added 2 commits June 17, 2026 11:51

Added PPMA data compression algorithm

5b583be

Added 2 URL sources

6bfef85

algorithms-keeper Bot added require tests Tests [doctest/unittest/pytest] are required require type hints https://docs.python.org/3/library/typing.html labels Jun 17, 2026

algorithms-keeper Bot reviewed Jun 17, 2026

View reviewed changes

algorithms-keeper Bot added the awaiting reviews This PR is ready to be reviewed label Jun 17, 2026

Added type hint for __init__

4fb09a8

algorithms-keeper Bot removed the require type hints https://docs.python.org/3/library/typing.html label Jun 17, 2026

algorithms-keeper Bot reviewed Jun 17, 2026

View reviewed changes


		return {"readable_output": output, "ranges": output_ranges}

		def decode_text(self, ranges: list) -> str:


		return decoded_text

		def _get_context_probs(self, order: int, context: str) -> tuple[dict, int]:


		return dict(counts), total_count

		def process_char(self, char: str) -> tuple:


		return output, output_ranges

		def _update_models(self, char: str) -> None:

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Nert53 commented Jun 17, 2026

Describe your change:

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