为什么字节文字符号不断出现？

Question

当我打印出该值时，它很好。但最后它给出了一个错误，因为 b' 把名字弄乱了。我正在读取文件 f0.txt、f1.txt；计划修改它们并用相同的名称保存它们。

尝试了a similar question here 提供的 utf-8 解码解决方案，但不起作用。

path ='/kaggle/input/'
print (path)
i = 1
part = 'f' + str(i)
print (part) #the byte literal symbol b' doesn't appear here
for i in range(0,3):
    part = 'f' + str(i)
    file_path = path + part + '.csv'
    print (file_path) # the byte literal symbol b' doesn't appear here too
    pd = pd.read_csv(file_path, delim_whitespace = True) # error in this line
    np.savetxt(part.txt, pd,fmt='%.18e', delimiter=',', newline='n', header='Time,ID,lat,long,speed',)

b'/kaggle/input/f0.csv' does not exist

命令

pd.read_csv('/kaggle/input/f2.txt', delim_whitespace = True) 

正在工作。

第一种情况的错误是：

FileNotFoundError                         Traceback (most recent call last)
<ipython-input-33-37d9e9ecc542> in <module>
      8     file_path = path + part + '.csv'
      9     print (file_path)
---> 10     pd = pd.read_csv(file_path, delim_whitespace = True)
     11     np.savetxt(part.txt, pd,fmt='%.18e', delimiter=',', newline='n', header='Time,ID,lat,long,speed',)
     12 

/opt/conda/lib/python3.6/site-packages/pandas/io/parsers.py in parser_f(filepath_or_buffer, sep, delimiter, header, names, index_col, usecols, squeeze, prefix, mangle_dupe_cols, dtype, engine, converters, true_values, false_values, skipinitialspace, skiprows, nrows, na_values, keep_default_na, na_filter, verbose, skip_blank_lines, parse_dates, infer_datetime_format, keep_date_col, date_parser, dayfirst, iterator, chunksize, compression, thousands, decimal, lineterminator, quotechar, quoting, escapechar, comment, encoding, dialect, tupleize_cols, error_bad_lines, warn_bad_lines, skipfooter, doublequote, delim_whitespace, low_memory, memory_map, float_precision)
    676                     skip_blank_lines=skip_blank_lines)
    677 
--> 678         return _read(filepath_or_buffer, kwds)
    679 
    680     parser_f.__name__ = name

/opt/conda/lib/python3.6/site-packages/pandas/io/parsers.py in _read(filepath_or_buffer, kwds)
    438 
    439     # Create the parser.
--> 440     parser = TextFileReader(filepath_or_buffer, **kwds)
    441 
    442     if chunksize or iterator:

/opt/conda/lib/python3.6/site-packages/pandas/io/parsers.py in __init__(self, f, engine, **kwds)
    785             self.options['has_index_names'] = kwds['has_index_names']
    786 
--> 787         self._make_engine(self.engine)
    788 
    789     def close(self):

/opt/conda/lib/python3.6/site-packages/pandas/io/parsers.py in _make_engine(self, engine)
   1012     def _make_engine(self, engine='c'):
   1013         if engine == 'c':
-> 1014             self._engine = CParserWrapper(self.f, **self.options)
   1015         else:
   1016             if engine == 'python':

/opt/conda/lib/python3.6/site-packages/pandas/io/parsers.py in __init__(self, src, **kwds)
   1706         kwds['usecols'] = self.usecols
   1707 
-> 1708         self._reader = parsers.TextReader(src, **kwds)
   1709 
   1710         passed_names = self.names is None

pandas/_libs/parsers.pyx in pandas._libs.parsers.TextReader.__cinit__()

pandas/_libs/parsers.pyx in pandas._libs.parsers.TextReader._setup_parser_source()

FileNotFoundError: File b'/kaggle/input/f0.csv' does not exist

Answer 1

即使这样也重现了您所看到的行为：

import pandas as pd

pd.pd.read_csv('test.csv')

假设您的工作文件夹中没有名为 test.csv 的文件，则会导致：

FileNotFoundError: [Errno 2] File b'test.csv' does not exist: b'test.csv'

因此，.read_csv() 方法似乎接受字符串作为文件名，但在使用它打开文件之前将其转换为字节序列，当失败时，这就是报告的值。

请注意，打印的值（即b'test.csv'）并不意味着b 现在是文件名的一部分。它只是表示“一个包含test.csv的字节序列”，将它与'test.csv'区分开来，没有b，这意味着“一个包含test.csv的字符串”。