What is zip function in Python?

zip function gets iterables as input and returns a tuple as output, it actually aggregates data:

zip(seq1 [, seq2 [...]]) -> [(seq1[0], seq2[0] ...), (...)]

Returns a list of tuples, where each tuple contains the i-th element from each of the argument sequences. The returned list is truncated in length to the length of the shortest argument sequence.

So the syntax is:

zip(*iterables)

The real world example:

numberList = [1, 2, 3]
strList = ['one', 'two', 'three']

# Two iterables are passed
result = zip(numberList, strList)

{(2, 'two'), (3, 'three'), (1, 'one')}

If number of elements differ:

numbersList = [1, 2, 3]

numbersTuple = ('ONE', 'TWO', 'THREE', 'FOUR')

result = zip(numbersList, numbersTuple)

print(set(result))
{(2, 'TWO'), (3, 'THREE'), (1, 'ONE')}

As you can see from above, list is truncated to the length of the shortest argument sequence numbersList.


You can also use zip to actually unzip data:

coordinate = ['x', 'y', 'z']
value = [3, 4, 5, 0, 9]

result = zip(coordinate, value)
resultList = list(result)
print(resultList)

c, v =  zip(*resultList)
print('c =', c)
print('v =', v)

The output:

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

#python #zip #unzip #iterators