*arg 代表可变个数参数 fun(something,something)
def fun(**arg):
** arg 允许键值对的可变个数参数 调用时fun(arg1 = something,arg2 = something)
看下面、。。。。
How to use *argsand **kwargs in Python
Date: 2008-01-03 | Modified:2012-12-20 | Tags:core,python | 94 Comments
Or,How to use variable length argumentlists in Python.
The special syntax,*argsand**kwargsin function definitions is used to pass a variable numberof arguments to a function. The single asterisk form (*args) is used to pass anon-keyworded, variable-length argument list, and the double asteriskform is used to pass akeyworded, variable-length argument list. Here is an example ofhow to use the non-keyworded form. This example passes one formal (positional)argument, and two more variable length arguments.
deftest_var_args(farg,*args):
print"formalarg:",farg
forarginargs:
print"another arg:",arg
test_var_args(1,"two",3)
Results:
formal arg: 1
another arg: two
another arg: 3
Here is an example of how to use the keyworded form.Again, one formal argument and two keyworded variable arguments are passed.
deftest_var_kwargs(farg,**kwargs):
print"formalarg:",farg
forkeyinkwargs:
print"another keyword arg:%s:%s"%(key,kwargs[key])
test_var_kwargs(farg=1,myarg2="two",myarg3=3)
Results:
formal arg: 1
another keyword arg: myarg2: two
another keyword arg: myarg3: 3
Using*argsand**kwargswhencallinga function
This special syntax can be used, not only in functiondefinitions, but also whencallinga function.
deftest_var_args_call(arg1,arg2,arg3):
print"arg1:",arg1
print"arg2:",arg2
print"arg3:",arg3
args=("two",3)
test_var_args_call(1,*args)
Results:
arg1: 1
arg2: two
arg3: 3
Here is an example using the keyworded form when callinga function:
deftest_var_args_call(arg1,arg2,arg3):
print"arg1:",arg1
print"arg2:",arg2
print"arg3:",arg3
kwargs={"arg3":3,"arg2":"two"}
test_var_args_call(1,**kwargs)
Results:
arg1: 1
arg2: two
arg3: 3
argmax是一种对函数求参数（集合）的函数。当有另一个函数y=f(x)时，若有结果x0=argmax(f(x))，则表示当函数f(x)取x=x0的时候，得到f(x)取值范围的最大值。
若有多个点使得f(x)取得相同的最大值，那么argmax(f(x))的结果就是一个点集。换句话说，argmax(f(x))是使得f(x)取得最大值所对应的变量点x(或x的集合）。arg即argument，此处意为“自变量”。
max和argmax：
y = f(t)是一般常见的函数式，如果给定一个t值，f（t）函数式会赋一个值给y。
y = max f(t)代表：y是f(t)函式所有的值中最大的output。
y = argmax f(t)代表：y是f(t)函式中，会产生最大output的那个参数t。
