“A brown mug next to a MacBook with lines of code on its screen” by Artem Sapegin on Unsplash
1. Unpacking a sequence into a separate variables.
So you have given a sequence(like array, string etc) and you want to extract it’s data into separate variable how will you do that?
This can be achieved with assignment operator, The syntax is very simple
# comma_separated_variables = sequence
# given a data in the form of list
data = ['Ravi', 21, (1996, 12, 5)]
# extract name, age, dob from data
name, age, dob = data
print(name) # Ravi
print(age) # 21
print(dob) # (1996, 12, 5)
# It works with any sequence eg.
s = 'hello'
a, b, _, c, d = s
print(b) # e2. Unpacking elements from iterables of arbitrary length
In this case you want to unpack N elements from an iterables but this time the length of iterables can be more than N. Here we can use Python * expression. To know more about * expression consider this question on stackoverflow.
grades = [5, 6, 7, 8, 9]
first, *middle, last = grades
print(first) # 5
print(last) # 9
print(middle) # [6, 7, 8]
# The variable associated with * will always be a list
# We also can't use two * expression like:
first, *middle, *last = grades # this will get an error
# More complex example
data = ('Ravi', 21, (5, 12, 1996))
# We need only name and year from data
name, *_, (*_, year) = data
print(name) # Ravi
print(year) # 1996