*Memos:
- My post explains variable assignment.
- My post explains iterable unpacking in variable assignment.
- My post explains
*
for iterable unpacking in function. - My post explains
**
for dictionary unpacking. - My post explains
*args
and**kwargs
in function.
You can use *
for iterable unpacking in a variable assignment as shown below:
*Memos:
- A
*
is an iterable unpacking operator. - A
*variable
can store zero or more values as a list in a variable assignment. - Only one
*variable
can be used in each expression of the left side of a variable assignment. - Zero or more
*iterables
can be passed to a function with the zero or more values unpacked from zero or more iterables.
*v1, v2, v3 = [0, 1, 2, 3, 4] *v1, v2, v3 = (0, 1, 2, 3, 4) v1, v2, *v3 = [0, 1, 2, 3, 4] v1, *v2, v3 = [0, 1, 2, 3, 4] v1, *v2, v3 = [0, 1, 2, 3] v1, *v2, v3 = [0, 1, 2] v1, *v2, v3 = [0, 1] # No error *v1, v2, *v3 = [0, 1, 2, 3, 4] # SyntaxError: multiple starred expressions in assignment v1, *v2, v3 = [0] # ValueError: not enough values to unpack (expected at least 2, got 1)
*v1, = [] *v1, = 5, # Tuple *v1, = (5,) # No error *v1, = [0, 1, 2] *v2 = *v1 # SyntaxError: can't use starred expression here *v1 = [] # SyntaxError: starred assignment target must be in a list or tuple *v1, = 5 # TypeError: cannot unpack non-iterable int object
*v1, v2, v3 = [0, 1, 2, 3, 4] *v1, v2, v3 = (0, 1, 2, 3, 4) print(v1, v2, v3) # [0, 1, 2] 3 4 print(*v1, v2, v3) # 0 1 2 3 4
v1, v2, *v3 = [0, 1, 2, 3, 4] print(v1, v2, v3) # 0 1 [2, 3, 4] print(v1, v2, *v3) # 0 1 2 3 4
v1, *v2, v3 = [0, 1, 2, 3, 4] print(v1, v2, v3) # 0 [1, 2, 3] 4 print(v1, *v2, v3) # 0 1 2 3 4
v1, *v2, v3 = [0, 1, 2, 3] print(v1, v2, v3) # 0 [1, 2] 3 print(v1, *v2, v3) # 0 1 2 3
v1, *v2, v3 = [0, 1, 2] print(v1, v2, v3) # 0 [1] 2 print(v1, *v2, v3) # 0 1 2
v1, *v2, v3 = [0, 1] print(v1, v2, v3) # 0 [] 1 print(v1, *v2, v3) # 0 1
*v1, = [0, 1, 2] print(v1) # [0, 1, 2] print(*v1) # 0 1 2
*v1, = [] print(v1) # [] print(*v1) # Nothing
*v1, = 5, # Tuple print(v1) # [5] print(*v1) # 5
By default, one or more keys can be assigned to one or more variables from a dictrionary same as using keys() as shown below:
*v1, v2 = {'name":"John", "age":36, "gender":"Male"} *v1, v2 = {"name":"John", "age":36, "gender":"Male"}.keys() print(v1, v2) # ['name', 'age'] gender print(*v1, v2) # name age gender
One or more values can be assigned to one or more variables from a dictionary with values() as shown below:
*v1, v2 = {"name":"John", "age":36, "gender":"Male"}.values() print(v1, v2) # ['John', 36] Male print(*v1, v2) # John 36 Male
One or more keys and values can be assigned to one or more variables from a dictionary with items() as shown below:
*v1, v2 = {"name":"John", "age":36, "gender":"Male"}.items() print(v1, v2) # [('name', 'John'), ('age', 36)] ('gender', 'Male') print(*v1, v2) # ('name', 'John') ('age', 36) ('gender', 'Male') print(v1[0], v1[1], v2[0], v2[1]) # ('name', 'John') ('age', 36) gender Male print(*v1[0], *v1[1], v2[0], v2[1]) # name John age 36 gender Male
One or more characters can be assigned to one or more variables from a string as shown below:
v1, v2, *v3 = "Hello" print(v1, v2, v3) # H e ['l', 'l', 'o'] print(v1, v2, *v3) # H e l l o
*Again, zero or more *iterables
can be passed to a function with the zero or more values unpacked from zero or more iterables.
print(*[0, 1, 2]) print(*(0, 1, 2)) print(*range(3)) # 0 1 2 print(*'Hello') # H e l l o print([[0, 1, 2], 'Hello']) # [[0, 1, 2], 'Hello'] print(*[[0, 1, 2], 'Hello']) # [0, 1, 2] Hello print([*[0, 1, 2], *'Hello']) # [0, 1, 2, 'H', 'e', 'l', 'l', 'o'] print(*[*[0, 1, 2], *'Hello']) # 0 1 2 H e l l o
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