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What is the use of the "chain.from_iterable" function in Python?

The chain.from_iterable() function is a specific variation of the chain() function from the itertools module in Python. It is used to combine multiple iterables into a single iterator, similar to the chain() function. However, chain.from_iterable() expects a single iterable that contains several sub-iterables, and it flattens these sub-iterables into a single iterator.

The primary use of chain.from_iterable() is to handle a nested iterable structure and produce a flattened iterator. It is particularly useful when you have an iterable of iterables and you want to treat it as a single sequence, avoiding the need to manually iterate over each sub-iterable.

Here's an example to illustrate the usage of chain.from_iterable():

import itertools

nested_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

flattened_iterator = itertools.chain.from_iterable(nested_list)

for item in flattened_iterator:
    print(item)

# Output: 1 2 3 4 5 6 7 8 9

In this example, the nested_list contains three sub-lists. The chain.from_iterable() function is used to flatten these sub-lists into a single iterator called flattened_iterator. The for loop then iterates over flattened_iterator and prints each element, resulting in the output 1 2 3 4 5 6 7 8 9.

By utilizing chain.from_iterable(), you can efficiently handle nested iterable structures and seamlessly iterate over their elements as if they were part of a single sequence. It simplifies the process of flattening nested iterables and enables easy access to the individual elements within them.

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