1 files changed, 79 insertions, 0 deletions
diff --git a/flashcards-project/src/flashcards/scheduler_brutal.py b/flashcards-project/src/flashcards/scheduler_brutal.py
new file mode 100644
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--- /dev/null
+++ b/flashcards-project/src/flashcards/scheduler_brutal.py
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+from random import shuffle
+
+from .scheduler import Scheduler
+from .card import Card
+
+HISTORY_DEPTH = 8
+
+class SchedulerBrutal(Scheduler):
+    """
+    The brutal scheduler tracks how well the player has consolidated each card
+    and also how often the card has been shown. 
+
+    Using this information, it prioritizes cards that have been shown less
+    frequently and recently, which means the player will often see totally new
+    cards in test sessions.
+    """
+    def __init__(self, cards: dict[str, Card], state: dict):
+        self._cards = cards
+        self._state = {}
+
+        # Synchronise state with current card collection
+        for id, card in self._cards.items():
+            history = state.get(id, [None] * HISTORY_DEPTH)
+
+            # Adjust history if depth has changed
+            if len(history) > HISTORY_DEPTH:
+                history = history[-HISTORY_DEPTH:]
+            elif len(history) < HISTORY_DEPTH:
+                history = ([None] * (HISTORY_DEPTH - len(history))) + history
+
+            self._state[id] = history
+
+    def practice(self, size: int) -> list[str]:
+        return self._schedule(size)
+
+    def test(self, size: int) -> list[str]:
+        return self._schedule(size)
+
+    def update(self, results: dict[str, int]) -> None:
+        # Add card result to sliding window, or None if card was not shown
+        self._state = {id: history[1:] + [results.get(id, None)] 
+                       for id, history in self._state.items()}
+
+    def getState(self) -> dict:
+        return self._state
+
+    @staticmethod
+    def _consolidationIndex(history: list, weights: range) -> float:
+        """
+        Consolidation index is a measure of how well the player has guessed the card recently
+        """
+        relevant_history = [(h, w) for h, w in zip(history, weights) if h is not None]
+        weighted_history = sum([h * w for h, w in relevant_history])
+        total_weights = sum([w for h, w in relevant_history])
+        return weighted_history / total_weights if total_weights > 0 else 0.0
+
+    @staticmethod
+    def _exposureIndex(history: list) -> float:
+        """
+        Exposure index is a measure of how much and how recently a card has been shown
+        """
+        return sum([i + 1 for i, h in enumerate(history) if h is not None])
+
+    def _schedule(self, size: int) -> list[str]:
+        weights = range(10, 10 + HISTORY_DEPTH)
+        cards = [id for id, card in self._cards.items()]
+
+        # First sort by consolidation index
+        cards.sort(key=lambda id: SchedulerBrutal._consolidationIndex(self._state[id], weights))
+
+        # Next sort by exposure index
+        cards.sort(key=lambda id: SchedulerBrutal._exposureIndex(self._state[id]))
+
+        # Return least exposed and least consolidated cards, shuffled
+        cards = cards[0:size]
+
+        shuffle(cards)
+
+        return cards