Python:无法将 'bytes' 对象隐式转换为 str

Question

这是我的代码:

class ReviewCategoryClassifier(object):
      @classmethod
      def load_data(cls, input_file):
           job = category_predictor.CategoryPredictor()
           category_counts = None
           word_counts = {}

           with open(input_file) as src:
              for line in src:
                category, counts = job.parse_output_line(line)

      def __init__(self, input_file):
      """input_file: the output of the CategoryPredictor job."""
           category_counts, word_counts = self.load_data(input_file)

           self.word_given_cat_prob = {}
           for cat, counts in word_counts.iteritems():
               self.word_given_cat_prob[cat] = self.normalize_counts(counts)

              # filter out categories which have no words
               seen_categories = set(word_counts)
               seen_category_counts = dict((cat, count) for cat, count in 
                                      category_counts.iteritems() \
                                            if cat in seen_categories)
               self.category_prob= self.normalize_counts(
                                                      seen_category_counts)

if __name__ == "__main__":
     input_file = sys.argv[1]
     text = sys.argv[2]
     guesses = ReviewCategoryClassifier(input_file).classify(text)

顺便说一句，CategoryPredictor() 是一个 mrjob 项目。

每当我输入

python predict.py yelp_academic_dataset_review.json 'I like donut'

在命令行中，出现错误:

TypeError: Can't convert 'bytes' object to str implicitly

但是 line 是一个字符串而不是一个字节对象。我做错了什么？

这是完整的回溯

Traceback (most recent call last):
File "predict.py", line 116, in <module>
  guesses = ReviewCategoryClassifier(input_file).classify(text)
File "predict.py", line 65, in __init__
  category_counts, word_counts = self.load_data(input_file)
File "predict.py", line 44, in load_data
  category, counts = job.parse_output_line(line)
File "//anaconda/lib/python3.5/site-packages/mrjob/job.py", line 961, in 
    parse_output_line
return self.output_protocol().read(line)
File "//anaconda/lib/python3.5/site-packages/mrjob/protocol.py", line 84, in 
  read
       raw_key, raw_value = line.split(b'\t', 1)
TypeError: Can't convert 'bytes' object to str implicitly

Answer 1

您需要将字节传递给 MRJob.parse_output_line ;以二进制模式打开 input_file

with open(input_file, 'rb') as src:
    for line in src:
        category, counts = job.parse_output_line(line)

或者在传递给方法之前对行进行编码:

with open(input_file) as src:
    for line in src:
        category, counts = job.parse_output_line(line.encode())