Can you give a more simplified explanation of these two methods chain() and chain.from_iterable from itertools?
I have searched the knowledge base and as well the python documentation but i got confused.
I am new to python that's why I am asking a more simplified explanation regarding these.
Thanks!
You can chain sequences to make a single sequence:
>>> from itertools import chain
>>> a = [1, 2, 3]
>>> b = ['a', 'b', 'c']
>>> list(chain(a, b))
[1, 2, 3, 'a', 'b', 'c']
If a and b are in another sequence, instead of having to unpack them and pass them to chain you can pass the whole sequence to from_iterable:
>>> c = [a, b]
>>> list(chain.from_iterable(c))
[1, 2, 3, 'a', 'b', 'c']
It creates a sequence by iterating over the sub-sequences of your main sequence. This is sometimes called flattening a list. If you want to flatten lists of lists of lists, you'll have to code that yourself. There are plenty of questions and answers about that on Stack Overflow.
We can learn about the difference between these two tools by looking at the docs.
def chain(*iterables):
# chain('ABC', 'DEF') --> A B C D E F
...
def from_iterable(iterable):
# chain.from_iterable(['ABC', 'DEF']) --> A B C D E F
...
The key difference is in the signatures and how they handle an iterable, which is something that can be iterated or looped over.
chain accepts iterables, such as "ABC", "DEF" or [1, 2, 3], [7, 8, 9].chain.from_iterable accepts one iterable, often a nested iterable, e.g. "ABCDEF" or [1, 2, 3, 7, 8, 9]. This is helpful for a flattening nested iterables. See its direct implementation in the flatten tool found in the itertools recipes.
