How to flatten inner tuples in a list containing tuples of a two-item tuple and a single item

user_9921105 0
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I want to know if there is any efficient way to convert a list containing tuples of a two-item tuple and a single item into a flattened list or NumPy array?

list = [((-1, -1), -1), ((-1, -1), 0), ((-1, -1), 1), ((-1, -1), 2), ...]

The result I want is:

new_list = [[-1, -1, -1], [-1, -1, 0], [-1, -1, 1], [-1, -1, 2], ...]

So far, I have tried to use

new_list = [item for i in list for item in i]

But the result is comes out as:

[(-1, -1), -1, (-1, -1), 0, (-1, -1), 1, (-1, -1), 2, ...]

When I tried to remove the nested tuple, I got the error

TypeError: 'int' object is not iterable
list python
4 Answers

Since the structure of each of the tuples seems to be ((a, b), c), you can just use a list comprehension with tuple-unpacking:

>>> lst = [((-1, -1), -1), ((-1, -1), 0), ((-1, -1), 1), ((-1, -1), 2)]
>>> [[a, b, c] for ((a, b), c) in lst]
[[-1, -1, -1], [-1, -1, 0], [-1, -1, 1], [-1, -1, 2]]
user_16396250

Just a shorter one:

[[*x, y] for x, y in lst]
user_126710570

You need to keep the structure of the list (more or less). You're really flattening the nested elements, not the list itself. Unpacking is one simple way to go

new_lst = [[*x[0], x[1]] for x in lst]

Another is just explicit references:

new_lst = [[x[0][0], x[0][1], x[1]] for x in lst]
user_29887300

This should work assuming x = [((-1, -1), -1), ((-1, -1), 0), ((-1, -1), 1), ((-1, -1), 2), ...]

new_list = [list(i[0])+[i[1]] for i in x]
user_117873680
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