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If I have sequence of sequences (maybe a list of tuples) I can use itertools.chain() to flatten it. But sometimes I feel like I would rather write it as a comprehension. I just can't figure out how to do it. Here's a very construed case:
Let's say I want to swap the elements of every pair in a sequence. I use a string as a sequence here:
>>> from itertools import chain >>> seq = '012345' >>> swapped_pairs = zip(seq[1::2], seq[::2]) >>> swapped_pairs [('1', '0'), ('3', '2'), ('5', '4')] >>> "".join(chain(*swapped_pairs)) '103254' I use zip on the even and odd slices of the sequence to swap the pairs. But I end up with a list of tuples that now need to be flattened. So I use chain(). Is there a way I could express it with a comprehension instead?
If you want to post your own solution to the basic problem of swapping elements of the pairs, go ahead, I'll up-vote anything that teaches me something new. But I will only mark as accepted an answer that is targeted on my question, even if the answer is "No, you can't.".
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The itertools. from_iterable() method. The result of this function call is passed as the argument for the list() method which converts the sequence into a list. The final flattened list is printed using the code print("Flatten List:",listflat).
A simple and straightforward solution is to append items from sublists in a flat list using two nested for loops. A more compact and Pythonic solution is to use chain() function from itertools module.
With a comprehension? Well...
>>> seq = '012345' >>> swapped_pairs = zip(seq[1::2], seq[::2]) >>> ''.join(item for pair in swapped_pairs for item in pair) '103254' If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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