Added 2 types of masking

Project_Model/Libs/Transformer/Classes/TokenMasker.py

@@ -0,0 +1,77 @@
+import random
+import sys
+
+
+class TokenMasker:
+
+    def __init__(
+        self,
+        change_token_probability: float = 0.15,
+        mask_token_probability: float = 0.8,
+        random_token_prob: float = 0.1,
+        seed: int = random.randint(0, sys.maxsize),
+    ) -> None:
+
+        if change_token_probability < 0 or change_token_probability > 1:
+            raise ValueError("received a value that is not between 0 or 1")
+
+        if mask_token_probability < 0 or mask_token_probability > 1:
+            raise ValueError("received a value that is not between 0 or 1")
+
+        if random_token_prob < 0 or random_token_prob > 1:
+            raise ValueError("received a value that is not between 0 or 1")
+
+        if mask_token_probability + random_token_prob > 1:
+            raise ValueError("The sum of probabilities is over 1")
+
+        self.__change_token_probability = change_token_probability
+        self.__mask_token_probability = mask_token_probability
+        self.__random_token_prob = random_token_prob
+        self.__rng = random.Random(seed)
+
+    def mask_sequence(
+        self, token_sequence: list[int], max_vocabulary: int, mask_id: int
+    ) -> list[int]:
+
+        if mask_id <= max_vocabulary:
+            raise ValueError("mask_id is a value of vocabulary")
+
+        MASKED_SEQUENCE: list[int] = []
+
+        for token in token_sequence:
+
+            if token > max_vocabulary:
+                MASKED_SEQUENCE.append(token)
+                continue
+
+            MASKED_TOKEN = self.__mask(token, max_vocabulary, mask_id)
+            MASKED_SEQUENCE.append(MASKED_TOKEN)
+
+        return MASKED_SEQUENCE
+
+    def __mask(self, token: int, max_vocabulary: int, mask_id: int) -> int:
+
+        if self.__random_probability() > self.__change_token_probability:
+            return token
+
+        MASK_TOKEN_TRESH = self.__mask_token_probability
+        RANDOM_TOKEN_TRESH = MASK_TOKEN_TRESH + self.__random_token_prob
+        CHANCE_PROBABILITY = self.__random_probability()
+
+        # It's over both probabilities, return same token
+        if CHANCE_PROBABILITY > RANDOM_TOKEN_TRESH:
+            return token
+
+        # It's over masking treshold, but lower than random
+        #   return random token
+        if CHANCE_PROBABILITY > MASK_TOKEN_TRESH:
+            return self.__random_token(max_vocabulary)
+
+        # It's below masking treshold, mask token
+        return mask_id
+
+    def __random_probability(self) -> float:
+        return self.__rng.random()
+
+    def __random_token(self, max_vocabulary: int) -> int:
+        return self.__rng.randint(0, max_vocabulary)