Python zip() and unzip() Functions

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Index

• Zip: 1. Definition 2. Syntax 3. Parameter Values 4. Return Values

• UnZipping:

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Zip

Definition

The zip() function returns a zip object, which is an iterator of tuples where the first item in each passed iterator is paired together, and then the second item in each passed iterator are paired together etc.

If the passed iterators have different lengths, the iterator with the least items decides the length of the new iterator.

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Syntax

zip(iterator1, iterator2, iterator3 ...)

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Parameter Values

Parameter	Description
iterator1, iterator2, iterator3 …	Iterator objects that will be joined together

oss: can be built-in iterables (like: list, string, dict), or user-defined iterables

Recommended Reading: [[Python Iterators, iter and next]]

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Return Values

The zip() function returns an iterator of tuples based on the iterable objects.

1. If we do not pass any parameter, zip() returns an empty iterator

2. If a single iterable is passed, zip() returns an iterator of tuples with each tuple having only one element.

3. If multiple iterables are passed, zip() returns an iterator of tuples with each tuple having elements from all the iterables.

   Suppose, two iterables are passed to zip(); one iterable containing three and other containing five elements. Then, the returned iterator will contain three tuples. It’s because the iterator stops when the shortest iterable is exhausted.

Examples no parameters:

result = (zip())
 
# oss: use a list/tuple funcione too make the zip object readable
print(tuple(result))
# Output: ()

Examples one parameters:

list = [1, 2, 3, 4]
result = (zip(list))
 
# oss: use a list/tuple funcione too make the zip object readable
print(list(result))
# Output: [(1,), (2,), (3,), (4,)]

Examples multiple parameters (same length):

languages = ['Java', 'Python', 'JavaScript']
versions = [14, 3, 6]
 
result = zip(languages, versions)
 
print(list(result))
# Output: [('Java', 14), ('Python', 3), ('JavaScript', 6)]

Examples multiple parameters (different length):

languages = ['Java', 'Python', 'JavaScript']
versions = [14, 3, 6]
difficulty = [1000]
 
result = zip(languages, versions, difficulty)
 
print(list(result))
# Output: [('Java', 14, 100)]

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UnZipping

coordinate = ['x', 'y', 'z']
value = [3, 4, 5]
 
result = zip(coordinate, value)
result_list = list(result)
print(result_list)
 
c, v =  zip(*result_list)
print('c =', c)
print('v =', v)

Output:

[('x', 3), ('y', 4), ('z', 5)]
c = ('x', 'y', 'z')
v = (3, 4, 5)

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