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Comprehensions & generators

List/dict/set comprehensions, generator expressions, and lazy iteration.

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Comprehensions & generators easy

How to Accumulate Values with a Generator in Python

This generator yields the running total of an iterable's elements, producing a cumulative sum with each step.

generator accumulate cumulative-sum
Python 
def accum(iterable):
    total = 0
    for item in iterable:
        total += item
        yield total

# Demo
if __name__ == "__main__":
    data = [1, 2, 3, 4, 5]
    print(list(accum(data)))  # [1, 3, 6, 10, 15]

    # Also works with any iterable, e.g., range
    print(list(accum(range(1, 6))))  # [1, 3, 6, 10, 15]
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