Merge pull request #65 from zafstojano/env/group-anagrams

Group Anagrams together

reasoning_gym/algorithmic/__init__.py

@@ -8,6 +8,7 @@ Algorithmic tasks for training reasoning capabilities:
 
 from .base_conversion import BaseConversionConfig, BaseConversionDataset
 from .caesar_cipher import CaesarCipherConfig, CaesarCipherDataset
+from .group_anagrams import GroupAnagramsConfig, GroupAnagramsDataset
 from .letter_counting import LetterCountingConfig, LetterCountingDataset
 from .letter_jumble import LetterJumbleConfig, LetterJumbleDataset
 from .number_filtering import NumberFilteringConfig, NumberFilteringDataset
@@ -45,4 +46,6 @@ __all__ = [
     "WordLadderDataset",
     "PalindromeConfig",
     "PalindromeDataset",
+    "GroupAnagramsConfig",
+    "GroupAnagramsDataset",
 ]

reasoning_gym/algorithmic/group_anagrams.py

@@ -0,0 +1,136 @@
+"""Group all anagrams together in a list.
+
+Anagram is a word formed by rearranging the letters of a different word, using all the original letters exactly once.
+
+A popular Leetcode problem:
+https://leetcode.com/problems/group-anagrams/description/
+"""
+
+import json
+from collections import defaultdict
+from dataclasses import dataclass
+from random import Random
+from typing import Dict, Optional
+
+from ..data import get_data_file_path
+from ..factory import ProceduralDataset, register_dataset
+
+MAX_ANAGRAM_GROUPS = 500
+
+QUESTION_TEMPLATE = """An anagram is a word formed by rearranging the letters of a different word, using all the original letters exactly once.
+
+Your job is to group the anagrams together. You can return the answer in any order.
+
+Example:
+Input: ["eat", "tea", "tan", "ate", "nat", "bat"]
+Output: [["bat"], ["nat", "tan"], ["ate", "eat", "tea"]]
+Explanation:
+    - There is no string in the input that can be rearranged to form "bat".
+    - The strings "nat" and "tan" are anagrams as they can be rearranged to form each other.
+
+Group the following list of words into anagrams:
+{words}
+"""
+
+
+@dataclass
+class GroupAnagramsConfig:
+    """Configuration for Group Anagrams dataset generation"""
+
+    anagram_groups: int = 10  # Groups of anagrams present in the input
+    max_words_per_group: int = 5  # Maximum number of words in a single anagram group
+
+    size: int = 500  # Virtual dataset size
+    seed: Optional[int] = None
+
+    def validate(self):
+        """Validate configuration parameters"""
+        assert (
+            1 <= self.anagram_groups <= MAX_ANAGRAM_GROUPS
+        ), f"anagram_groups must be between 1 and {MAX_ANAGRAM_GROUPS}"
+        assert 1 <= self.max_words_per_group, "max_words_per_group must be at least 1"
+
+
+class GroupAnagramsDataset(ProceduralDataset):
+    """Generates Group Anagrams exercises with configurable difficulty"""
+
+    def __init__(self, config: GroupAnagramsConfig):
+        super().__init__(config=config, seed=config.seed, size=config.size)
+        with get_data_file_path("anagrams.jsonl").open() as f:
+            self.anagrams = [json.loads(line)["words"] for line in f]
+
+    def __len__(self) -> int:
+        return self.config.size
+
+    def __iter__(self):
+        self._current_idx = 0
+        return self
+
+    def __next__(self):
+        if self._current_idx >= self.config.size:
+            raise StopIteration
+        item = self[self._current_idx]
+        self._current_idx += 1
+        return item
+
+    def _get_anagram_words(self, rng: Random) -> list[str]:
+        """Generate a list of words with anagrams"""
+        words = []
+        for sample in rng.sample(self.anagrams, self.config.anagram_groups):
+            anagrams = rng.sample(sample, rng.randint(1, min(len(sample), self.config.max_words_per_group)))
+            words.extend(anagrams)
+        return words
+
+    def _sort_nested_list(self, lst: list[list[str]]) -> list[list[str]]:
+        """Sort a nested list of strings"""
+        return sorted([sorted(sublist) for sublist in lst], key=lambda x: x[0] if x else "")
+
+    def _group_anagrams(self, words: list[str]) -> list[list[str]]:
+        """Group anagrams together"""
+
+        def _codify(word):
+            code = [0] * 26
+            for c in word:
+                code[ord(c) - ord("a")] += 1
+            return tuple(code)
+
+        res = defaultdict(list)
+        for word in words:
+            code = _codify(word)
+            res[code].append(word)
+
+        anagrams = list(res.values())
+        return self._sort_nested_list(anagrams)
+
+    def score_answer(self, answer: Optional[str], entry: Dict[str, any]) -> float:
+        """Score a single Group Anagrams question"""
+        reward = 0
+        if answer is not None:
+            try:
+                answer = json.loads(answer)
+                oracle = entry["metadata"]["solution"]
+                answer_str = json.dumps(self._sort_nested_list(answer))
+                oracle_str = json.dumps(self._sort_nested_list(oracle))
+                if answer_str == oracle_str:
+                    reward = 1
+                else:
+                    reward = 0.01
+            except Exception:
+                reward = 0
+        return reward
+
+    def __getitem__(self, idx: int) -> dict:
+        """Generate a single Group Anagrams question"""
+        rng = Random(self.seed + idx)
+        words = self._get_anagram_words(rng)
+        answer = self._group_anagrams(words)
+        answer_str = json.dumps(answer)
+
+        return {
+            "question": QUESTION_TEMPLATE.format(words=json.dumps(words)),
+            "answer": answer_str,
+            "metadata": {"words": words, "solution": answer},
+        }
+
+
+register_dataset("group_anagrams", GroupAnagramsDataset, GroupAnagramsConfig)