DAY 25 异常处理

1.异常处理机制

2.debug过程中的各类报错

def my_function()print('Hello')

  Cell In[1], line 1def my_function()^
SyntaxError: invalid syntax

x = 5 +print(x)

  Cell In[2], line 1x = 5 +^
SyntaxError: invalid syntax

print(some_undefined_variable)

---------------------------------------------------------------------------NameError                                 Traceback (most recent call last)Cell In[3], line 1
----> 1 print(some_undefined_variable)NameError: name 'some_undefined_variable' is not defined

print(my_lisst)

---------------------------------------------------------------------------NameError                                 Traceback (most recent call last)Cell In[4], line 1
----> 1 print(my_lisst)NameError: name 'my_lisst' is not defined

print('Age: ' + 25)my_number = 10
my_number()

---------------------------------------------------------------------------TypeError                                 Traceback (most recent call last)Cell In[5], line 1
----> 1 print('Age: ' + 25)3 my_number = 104 my_number()TypeError: can only concatenate str (not "int") to str

my_string = '12.34.56'
number = float(my_string)

---------------------------------------------------------------------------ValueError                                Traceback (most recent call last)Cell In[6], line 21 my_string = '12.34.56'
----> 2 number = float(my_string)ValueError: could not convert string to float: '12.34.56'

data = ('apple', 'banana')print(data[2])

---------------------------------------------------------------------------IndexError                                Traceback (most recent call last)Cell In[7], line 31 data = ('apple', 'banana')
----> 3 print(data[2])IndexError: tuple index out of range

student_grades = {'math': 90, 'science': 85}print(student_grades['history'])

---------------------------------------------------------------------------KeyError                                  Traceback (most recent call last)Cell In[8], line 31 student_grades = {'math': 90, 'science': 85}
----> 3 print(student_grades['history'])KeyError: 'history'

a_string = 'hello'print(a_string.length)

---------------------------------------------------------------------------AttributeError                            Traceback (most recent call last)Cell In[9], line 31 a_string = 'hello'
----> 3 print(a_string.length)AttributeError: 'str' object has no attribute 'length'

import numpy as nparr = np.array([1, 2, 3])print(arr.non_existent_attribute)

---------------------------------------------------------------------------AttributeError                            Traceback (most recent call last)Cell In[10], line 51 import numpy as np3 arr = np.array([1, 2, 3])
----> 5 print(arr.non_existent_attribute)AttributeError: 'numpy.ndarray' object has no attribute 'non_existent_attribute'

result = 10 / 0result

---------------------------------------------------------------------------ZeroDivisionError                         Traceback (most recent call last)Cell In[11], line 1
----> 1 result = 10 / 03 resultZeroDivisionError: division by zero

import pandas as pddata = pd.read_csv('hh.csv')

---------------------------------------------------------------------------FileNotFoundError                         Traceback (most recent call last)Cell In[12], line 31 import pandas as pd
----> 3 data = pd.read_csv('hh.csv')File c:\Users\36352\.conda\envs\kk\lib\site-packages\pandas\io\parsers\readers.py:1026, in read_csv(filepath_or_buffer, sep, delimiter, header, names, index_col, usecols, dtype, engine, converters, true_values, false_values, skipinitialspace, skiprows, skipfooter, nrows, na_values, keep_default_na, na_filter, verbose, skip_blank_lines, parse_dates, infer_datetime_format, keep_date_col, date_parser, date_format, dayfirst, cache_dates, iterator, chunksize, compression, thousands, decimal, lineterminator, quotechar, quoting, doublequote, escapechar, comment, encoding, encoding_errors, dialect, on_bad_lines, delim_whitespace, low_memory, memory_map, float_precision, storage_options, dtype_backend)1013 kwds_defaults = _refine_defaults_read(1014     dialect,1015     delimiter,(...)1022     dtype_backend=dtype_backend,1023 )1024 kwds.update(kwds_defaults)
-> 1026 return _read(filepath_or_buffer, kwds)File c:\Users\36352\.conda\envs\kk\lib\site-packages\pandas\io\parsers\readers.py:620, in _read(filepath_or_buffer, kwds)617 _validate_names(kwds.get("names", None))619 # Create the parser.
--> 620 parser = TextFileReader(filepath_or_buffer, **kwds)622 if chunksize or iterator:623     return parserFile c:\Users\36352\.conda\envs\kk\lib\site-packages\pandas\io\parsers\readers.py:1620, in TextFileReader.__init__(self, f, engine, **kwds)1617     self.options["has_index_names"] = kwds["has_index_names"]1619 self.handles: IOHandles | None = None
-> 1620 self._engine = self._make_engine(f, self.engine)File c:\Users\36352\.conda\envs\kk\lib\site-packages\pandas\io\parsers\readers.py:1880, in TextFileReader._make_engine(self, f, engine)1878     if "b" not in mode:1879         mode += "b"
-> 1880 self.handles = get_handle(1881     f,1882     mode,1883     encoding=self.options.get("encoding", None),1884     compression=self.options.get("compression", None),1885     memory_map=self.options.get("memory_map", False),1886     is_text=is_text,1887     errors=self.options.get("encoding_errors", "strict"),1888     storage_options=self.options.get("storage_options", None),1889 )1890 assert self.handles is not None1891 f = self.handles.handleFile c:\Users\36352\.conda\envs\kk\lib\site-packages\pandas\io\common.py:873, in get_handle(path_or_buf, mode, encoding, compression, memory_map, is_text, errors, storage_options)868 elif isinstance(handle, str):869     # Check whether the filename is to be opened in binary mode.870     # Binary mode does not support 'encoding' and 'newline'.871     if ioargs.encoding and "b" not in ioargs.mode:872         # Encoding
--> 873         handle = open(874             handle,875             ioargs.mode,876             encoding=ioargs.encoding,877             errors=errors,878             newline="",879         )880     else:881         # Binary mode882         handle = open(handle, ioargs.mode)FileNotFoundError: [Errno 2] No such file or directory: 'hh.csv'

import hhh

---------------------------------------------------------------------------ModuleNotFoundError                       Traceback (most recent call last)Cell In[13], line 1
----> 1 import hhhModuleNotFoundError: No module named 'hhh'

3.try-except机制

numerator = 10
denominator = 0
result = numerator / denominatorprint(f'结果是: {result}')
print('这行代码不会执行，因为程序已崩溃')

---------------------------------------------------------------------------ZeroDivisionError                         Traceback (most recent call last)Cell In[14], line 31 numerator = 102 denominator = 0
----> 3 result = numerator / denominator5 print(f'结果是: {result}')6 print('这行代码不会执行，因为程序已崩溃')ZeroDivisionError: division by zero

print('使用 try-except 捕获 ZeroDivisionError')numerator = 10
denominator = 0try:print('尝试进行除法运算...')result = numerator / denominatorprint(f'计算结果是: {result}')
except ZeroDivisionError:print('发生了一个除以零的错误！')result = '未定义 (除以零)'print(f'程序继续执行, 最终结果的记录为: {result}')

使用 try-except 捕获 ZeroDivisionError
尝试进行除法运算...
发生了一个除以零的错误！
程序继续执行, 最终结果的记录为: 未定义 (除以零)

x = 'hello'
y = 5
result = x + yprint(result)

---------------------------------------------------------------------------TypeError                                 Traceback (most recent call last)Cell In[16], line 31 x = 'hello'2 y = 5
----> 3 result = x + y5 print(result)TypeError: can only concatenate str (not "int") to str

print('使用 try-except 捕获 TypeError')x = 'Total items: '
y = 5try:print('尝试连接字符串和数字...')message = x + yprint(f'最终消息: {message}')
except TypeError:print('类型错误！不能直接将字符串和数字相加。')print('尝试将数字转换为字符串进行连接...')message = x + str(y)print(f'修正后的消息: {message}')print(f'程序继续, 生成的消息是: {message}')

使用 try-except 捕获 TypeError
尝试连接字符串和数字...
类型错误！不能直接将字符串和数字相加。
尝试将数字转换为字符串进行连接...
修正后的消息: Total items: 5
程序继续, 生成的消息是: Total items: 5

4.try-except-else-finally机制

print('try-except-else 示例')def safe_divide(a, b):print(f'\n尝试计算 {a} / {b}')try:result = a / bexcept ZeroDivisionError:print('错误：除数不能为零！')return Noneexcept TypeError:print('错误：输入必须是数字！')return Noneelse:print('除法运算成功！')print(f'结果是: {result}')print(f'结果的两倍是: {result * 2}')return resultsafe_divide(10, 2)
safe_divide(10, 0)
safe_divide('10', 2)
safe_divide(20, 'abc')

try-except-else 示例尝试计算 10 / 2
除法运算成功！
结果是: 5.0
结果的两倍是: 10.0尝试计算 10 / 0
错误：除数不能为零！尝试计算 10 / 2
错误：输入必须是数字！尝试计算 20 / abc
错误：输入必须是数字！

作业：理解今日的内容即可，可以检查自己过去借助ai写的代码是否带有try-except机制，以后可以尝试采用这类写法增加代码健壮性。

@浙大疏锦行