我这里有一个包含大字母句子的文件 “train.en”，我将它变成小字母句子，最后把它们输出到 “train_lower.en” 。它的代码如下：
def read_text_file(filename):
with open(filename, "r") as f:
output = [line.strip() for line in f]
return output
sen_list = []
path = 'train.en'
text = read_text_file(path)
sen_len = len(text)
for n in range(sen_len):
sen = text[n]
sen_str = str(sen)
sen = sen_str.lower()
sen_list.append(sen)
print(sen_list)
with open('train_lower.en', 'w', encoding='utf-8') as f:
f.write('n'.join(sen_list) + 'n')
