Generator pipelines in Python

Chaining generators so data flows through stages lazily.

def numbers(limit):
    for n in range(limit):
        yield n


def only_odd(source):
    for n in source:
        if n % 2:
            yield n


def scaled(source, factor):
    for n in source:
        yield n * factor


pipeline = scaled(only_odd(numbers(10)), 100)
result = list(pipeline)

How it works

1. Each yield hands one value downstream.
2. only_odd and scaled wrap the previous generator.
3. Nothing computes until list pulls the pipeline.

Keywords and builtins used here

• def
• for
• if
• list
• numbers
• only_odd
• range
• scaled
• yield

The run, in numbers

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At the three-star pace of 100 tokens a minute, this run takes about 43 seconds.

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Step 1 of 5 in Generators & itertools, step 10 of 53 in Pythonic Python.

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