Consume multiple iterators, filling each when exhausted with the last value they produced.

zip_longest_repeat_last.py

from itertools import repeat


def zip_longest_repeating(*iterables):
	"""Consume multiple iterables, filling each when exhausted with the last value they produced, until all are exhausted."""
	
	tracking = {}  # Track the last value seen for each iterable passed in.
	iterators = [iter(it) for it in iterables]
	count = len(iterators)
	if not count: return
	
	while True:
		values = []
		
		for i, it in enumerate(iterators):
			try:
				tracking[it] = next(it)
			except StopIteration:
				count -= 1
				if not count: return
				iterators[i] = repeat(tracking[it])
			
			values.append(tracking[it])
		
		yield tuple(values)


# Vs. https://gist.github.com/rendarz/cc2c99cdce4dc56d2f17e74342bfb241

Didn't initially see a point in zip_longest_repeating a single iterable, but there's no reason why not, thus the revision. No need to exclude programmatic use where the argument list is generated, and may be incidentally singular. Also terminology use.