Python帮助文档的使用
Python的一个优势是有着大量自带和在线的模块(module)资源,可以提供丰富的功能，在使用这些模块的时候，如果每次都去网站找在线文档会过于浪费时间，因此，我们可以使用IDLE里边自带的查看帮助功能，可以在编辑时不中断地迅速找到所需要模块和函数的使用方法。
通用帮助函数help
在Python命令行中键入help(), 就可以看到:
>>> help()
Welcome to Python 3.5's help utility!
If this is your first time using Python, you should definitely check out
the tutorial on the Internet at http://docs.python.org/3.5/tutorial/.
Enter the name of any module, keyword, or topic to get help on writing
Python programs and using Python modules. To quit this help utility and
return to the interpreter, just type "quit".
To get a list of available modules, keywords, symbols, or topics, type
"modules", "keywords", "symbols", or "topics". Each module also comes
with a one-line summary of what it does; to list the modules whose name
or summary contain a given string such as "spam", type "modules spam".进入help帮助文档界面, 根据屏幕提示可以继续键入相应的关键词进行查询, 继续键入modules可以列出当前所有安装的模块:
help> modules
Please wait a moment while I gather a list of all available modules...
AutoComplete _sqlite3 fnmatch pymsgbox
AutoCompleteWindow _sre formatter pyparsing
AutoExpand _ssl fractions pyperclip
Bindings _stat ftplib pyscreeze
CallTipWindow _string functools pytweening
CallTips _strptime gc queue
......
Enter any module name to get more help. Or, type "modules spam" to search
for modules whose name or summary contain the string "spam".可以继续键入相应的模块名称得到该模块的帮助信息. 这是Python通用的查询帮助, 可以查询到几乎所有的帮助文档, 但我们很多时候不需要这样层级式的向下查询,接下来介绍如何直接查询特定的模块 模块 和 函数 的帮助信息.
模块帮助查询
查看.py结尾的普通模块help(module_name)
例如查询math模块的使用方法,可以如下操作:
>>> import math
>>> help(math)
Help on built-in module math:
NAME
math
DESCRIPTION
This module is always available. It provides access to the
mathematical functions defined by the C standard.
FUNCTIONS
acos(...)
acos(x)
Return the arc cosine (measured in radians) of x.
acosh(...)
acosh(x)
Return the inverse hyperbolic cosine of x.
fabs(...)
fabs(x)
Return the absolute value of the float x.
factorial(...)
factorial(x) -> Integral
Find x!. Raise a ValueError if x is negative or non-integral.
DATA
e = 2.718281828459045
inf = inf
nan = nan
pi = 3.141592653589793
FILE
(built-in)
使用help(module_name)时首先需要import该模块, 不先进行导入可能会出出错
查看內间模块sys.builtin_module_name
>>> import sys
>>> sys.builtin_module_names
('_ast', '_bisect', '_codecs', '_codecs_cn', '_codecs_hk', '_codecs_iso2022', '_codecs_jp', '_codecs_kr', '_codecs_tw', '_collections', '_csv', '_datetime', '_functools', '_heapq', '_imp', '_io', '_json', '_locale', '_lsprof', '_md5', 'zipimport', 'zlib')需要导入sys模块. 这里列举的一般是自带的使用C/C++编译链接的模块
查询函数信息
查看模块下所有函数dir(module_name)
如我们需要列举出math模块下所有的函数名称
>>> dir(math)
['__doc__', '__loader__', '__name__', '__package__', '__spec__', 'acos', 'acosh', 'asin', 'asinh', 'atan', 'atan2', 'atanh', 'ceil', 'copysign', 'cos', 'cosh', 'degrees', 'e', 'erf', 'erfc', 'exp', 'expm1', 'fabs', 'factorial', 'floor', 'fmod', 'frexp', 'fsum', 'gamma', 'gcd', 'hypot', 'inf', 'isclose', 'isfinite', 'isinf', 'isnan', 'ldexp', 'lgamma', 'log', 'log10', 'log1p', 'log2', 'modf', 'nan', 'pi', 'pow', 'radians', 'sin', 'sinh', 'sqrt', 'tan', 'tanh', 'trunc']同样需要先导入模块
查看模块下特定函数信息help(module_name.func_name)
>>> help(math.sin)
Help on built-in function sin in module math:
sin(...)
sin(x)
Return the sine of x (measured in radians).查看函数信息的另一种方法print(func_name.doc)
>>> print(print.__doc__)
print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)
Prints the values to a stream, or to sys.stdout by default.
Optional keyword arguments:
file: a file-like object (stream); defaults to the current sys.stdout.
sep: string inserted between values, default a space.
end: string appended after the last value, default a newline.
flush: whether to forcibly flush the stream.__doc__前后是两个下划线, 在Python中会合并为长下划线