How to Repeat a Generator Cycle Single Value in Python
Build a generator that repeats a single value across multiple cycles, each cycle adding an extra repetition to mark its completion.
Python code
22 linesdef repeat_with_cycle(value, cycle_limit, repetitions):
"""
Repeats a single value until reaching a cycle limit,
then yields the value one more time to demonstrate a full cycle.
Args:
value: The single value to repeat.
cycle_limit: Number of repetitions per cycle.
repetitions: How many cycles to perform.
"""
for cycle in range(repetitions):
for _ in range(cycle_limit):
yield value
# Demonstrate completing the cycle by yielding the value once more
yield value # this marks the end of a cycle
if __name__ == "__main__":
# Repeat the number 7 for 3 cycles, each cycle repeating 2 times + 1 final
result = list(repeat_with_cycle(7, 2, 3))
print(result)
print(f"Total elements: {len(result)}")Output
[7, 7, 7, 7, 7, 7, 7, 7, 7]
Total elements: 9How it works
This generator uses nested loops to control the pattern: an outer loop runs repetitions times, and an inner loop yields the value cycle_limit times per cycle. After the inner loop, it yields the value once more to explicitly mark the cycle's end. By converting the generator output with list(), we materialize the lazy sequence and can inspect it directly. The generator pattern keeps memory usage low even for large repetition counts because values are produced on demand. This approach is flexible: changing value, cycle_limit, or repetitions produces a different patterned sequence without extra logic.
Common mistakes
- Forgetting the extra yield for the final element, which changes the expected total length.
- Using a list instead of a generator for very large sequences, causing high memory usage.
- Confusing cycle_limit with total repetitions, leading to off-by-one errors in expected output.
- Not wrapping the generator in `list()` when printing, which shows a generator object instead of values.
Variations
- Use `itertools.repeat` inside a loop: `for _ in range(repetitions): yield from repeat(value, cycle_limit + 1)`.
- Return a list directly for small fixed sizes: `[value] * (cycle_limit + 1) * repetitions`.
Real-world use cases
- Generating uniform sensor readings for test simulations where each sampling cycle is marked with an extra data point.
- Producing repeating schedule placeholders where each shift pattern ends with an additional confirmation signal.
- Creating repeated placeholder values in data pipelines when batching requires an explicit end-of-batch sentinel.
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