限制英文只有abcd

Author: matouxiao

itn/chinese/rules/cardinal.py

@@ -172,7 +172,7 @@ def build_tagger(self):
         # 5. 添加"中文数字+英文字母"的规则，如"四a" -> "4a"
         # 匹配一个或多个英文字母（大小写）
         from pynini import union
-        english_letters = union(*[accep(c) for c in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"])
+        english_letters = union(*[accep(c) for c in "abcdABCD"])
         # 数字+字母的组合，如"四a" -> "4a"
         number_with_letter = number + english_letters.plus
         cardinal |= add_weight(number_with_letter, 0.05)  # 使用较高优先级