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What I expect

Tokenizer should not tokenize characters listed in filters.

What happens

If char_level=True, Tokenizer will tokenize all characters—even those listed in filters.

Code

❯ text = "ae"
❯ tokenizer = keras.preprocessing.text.Tokenizer(filters="e")  # Ignore "e"
❯ tokenizer.fit_on_texts(text)
❯ tokenizer.word_index
{'a': 1}  # Ignores "e" as expected
❯ tokenizer = keras.preprocessing.text.Tokenizer(char_level=True, filters="e")
❯ tokenizer.fit_on_texts(text)
❯ tokenizer.word_index
{'a': 1, 'e': 2}  # "e" is tokenized