itertools.chain is said to convert chain('ABC', 'DEF') --> A B C D E F. Yet, I see that
>>> Set(itertools.chain([(1,2,3),(4,5,6)]))
Set([(4, 5, 6), (1, 2, 3)])
I see that no hierarchy is affected. Similarly, list(itertools.chain([[1,2,3],[4,5,6]])) is said to have effect on lists. But I see no flattening in my case
>>> list(itertools.chain([[1,2,3],[4,5,6]]))
[[1, 2, 3], [4, 5, 6]]
What the hell is going on?
What the hell is going on?
You misread the answer you referenced
In that answer was this line:
merged = list(itertools.chain(*list2d))
Note the use of the asterisk (or 'splat') operator.
In your question, there is no such operator:
>>> list(itertools.chain([[1,2,3],[4,5,6]]))
[[1, 2, 3], [4, 5, 6]]
To make sense of the answer you reference, try this:
>>> list(itertools.chain(*[[1,2,3],[4,5,6]]))
[1, 2, 3, 4, 5, 6]
Which is equivalent to removing the outer-most brackets:
>>> list(itertools.chain([1,2,3],[4,5,6]))
[1, 2, 3, 4, 5, 6]
The fist argument is a list of iterables (tuples) not one iterable. You can use chain.from_iterable() to flatten your list:
>>> from itertools import chain
>>> list(chain.from_iterable([(1,2,3),(4,5,6)]))
[1, 2, 3, 4, 5, 6]
