现在我们希望在另一个Python文件main.py中访问another_file.py中定义的变量my_variable: # main.py# 方法一:使用import语句importanother_fileprint(another_file.my_variable)# 方法二:使用from ... import ...语句fromanother_fileimportmy_variableprint(my_variable)# 方法三:使用exec()函数file_name="another...
sys.path is initialized from these locations:The directory containing the input script (or the current directory when no file is specified). PYTHONPATH (a list of directory names, with the same syntax as the shell variable PATH). The installation-dependent default. import 执行时,会尝试使用以下...
importsysimportshutilimportzipfilefrompathlibimportPathclassZipReplace:def__init__(self, filename, search_string, replace_string): self.filename = filename self.search_string = search_string self.replace_string = replace_string self.temp_directory = Path(f"unzipped-{filename}") 然后,我们为三个...
| 任何类型→浮点 |float( )|wholenumber=522``floatnumber=float(wholenumber)``print(floatnumber)| | 整数或浮点→字符串 |str( )|float_variable=float(2.15)``string_variable=str(float_variable)``print(string_variable)| | 字符串→列表 |列表()|greeting="Hello"``a_list=list(greeting)``print(...
importnumpyasnpdeftest(a):a[0]=np.nanm=[1,2,3]test(m)print(m) output: [nan, 2, 3] Note python has this really weird error if you define local variable in a function same name as the global variable, program will promptUnboundLocalError. ...
Python 2.7保持了对之前版本的全兼容,而且还包含了Python 3.0的新玩意(一些新特性需要通过“from __future__ import”来启用)。 如果想要在python2.7中使用:print('error happens!', file=sys.stderr)这样的语句,就需写上“ from __future__ import print_function” ...
Another way to use absolute imports is by specifying the full package name of the module you want to import. In this case, Python will start looking for the module from the top-level directory of your project. To import theavariable fromfile.pyintomain.pyusing absolute imports with the pack...
print number def anotherfunc(): # This raises an exception because the variable has not # been bound before printing. Python knows that it an # object will be bound to it later and creates a new, local # object instead of accessing the global one. print number number = 3 def yetanothe...
File "<stdin>", line 1, in <module> File "<stdin>", line 2, in foo UnboundLocalError: local variable 'lst' referenced before assignment 嗯?为什么foo2报错,而foo1没有问题呢? 原因和之前那个例子的一样,不过更加令人难以捉摸。foo1没有对lst进行赋值操作,而foo2做了。要知道,lst += [5]是lst...
) # 操作符后换行 result = (this_is_a_really_long_variable_name + another_long_variable_that_needs_to_be_concatenated) 2.2 格式化字符串与文档字符串 2.2.1 使用f-string进行格式化输出 f-string是Python 3.6及以上版本引入的一种新型字符串格式化方式,它允许在字符串字面量中嵌入表达式,极大地提高了...