the asterik * in python
Asterik in python is usually very confused for the beginner. Some times it appears one time before a variable like *args, some times it appears two times like **args.
Usually it appears in function definition:
1 2 | def func(*args1, **args2): pass |
* and ** allow arbitrary number of arguments. Here the *args is somehow like a tuple of arguments, **kwargs is like a dictionary of arguments.
1 2 3 4 5 | def func(*args, **kwargs): for member in args: print member for member in kwargs: print member,"\t", kwargs[member] |
let see the *args, call the function
1 | func(1,2,3) |
you will get the output:
1
2
3
you can also call the function with *args, the type of args should be a tuple or a list, * means decompose the tuple or list,
1 2 | args = (1,2,3)func(1,2,3) |
you will also get the same output
1
2
3
Analog to **kwargs
1 | func(name = "pangpang", age = "12", hobby = "sleeping") |
you will get the output:
hobby sleeping
age 12
name pangpang
This is equivalent to
1 2 | kwargs = {"name":"pangpang","age":"12", "hobby":"sleeping"}func(**kwargs) |
you will get the same output like above.
I put the code in Gist, you can download and try it.
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| def func(*args, **kwargs): | |
| for member in args: | |
| print member | |
| for member in kwargs: | |
| print member,"\t", kwargs[member] | |
| #call the function | |
| func(1,2,3) | |
| args = [1,2,3] | |
| func(*args) | |
| func(name = "pangpang", age = "12", hobby = "sleeping") | |
| kwargs = {"name":"pangpang","age":"12", "hobby":"sleeping"} | |
| func(**kwargs) | |