record= ('ACME', 50, 123.45, (12, 18, 2012))
name, *_, (*_, year) = record
print(name)
>>>'ACME'
print (year)
>>> 2012
print (*_)
>>> 12 18
So i started reading about unpacking tuples, lists and dictionaries. It said
Sometimes you might want to unpack values and throw them away. You can’t just specify a bare * when unpacking, but you could use a common throwaway variable name, such as _ or ign(ignored)
I didn't quite understand, so I tried to understand by visualizing my code on pythontutor.com but it didn't really "throwaway" the values assigned to *_, also I am unable to access the data " 50, 123.45". I am just starting, so please bear with me cause I am having a hard time understanding this.
"Use a common throwaway variable name" is the clue. *_ is unpacking (*) into a variable named _. The only thing that makes _ "throwaway" is that it is generally ignored. However, if you don't ignore it, it won't be a throwaway!
If you want to unpack multiple pieces, and still be able to access them separately, use different variable names. Your example:
>>> record= ('ACME', 50, 123.45, (12, 18, 2012))
>>> name, *_, (*_, year) = record
>>> print(name,year,*_)
ACME 2012 12 18
assigns the variable _ twice, so the later-assigned data 12,18 overwrites the earlier-assigned data 50,123.45. By contrast, consider:
>>> name, *_a, (*_b, year) = record
>>> print(*_a)
50 123.45 <-- the data you mentioned
>>> print(*_b)
12 18
In this example, _a and _b are separate variables that hold separate contents. The assignment
name, *_a, (*_b, year) = record
is exactly the same as
name, *extra1, (*extra2, year) = record
but with different names. Again, nothing about _ itself is magical.