coding-mentor-agent/kb/python-course-kb-practical-python/wiki/exercises/6-4-a-simple-generator.md

id, source_exercise_id, title, section, source_path, source_repo, source_commit, student_visible_solution, has_private_solution, skip

id	source_exercise_id	title	section	source_path	source_repo	source_commit	student_visible_solution	has_private_solution	skip
practical-python-6.4	6.4	A Simple Generator	6.2 Customizing Iteration	06_Generators/02_Customizing_iteration.md	https://github.com/dabeaz-course/practical-python	93dca856b41c61a0a0f85ae334116e4c125629ea	false	false	false

Exercise 6.4: A Simple Generator

Source: Practical Python Programming, 06_Generators/02_Customizing_iteration.md.

Exercise 6.4: A Simple Generator

If you ever find yourself wanting to customize iteration, you should always think generator functions. They're easy to write---make a function that carries out the desired iteration logic and use yield to emit values.

For example, try this generator that searches a file for lines containing a matching substring:

>>> def filematch(filename, substr):
        with open(filename, 'r') as f:
            for line in f:
                if substr in line:
                    yield line

>>> for line in open('Data/portfolio.csv'):
        print(line, end='')

name,shares,price
"AA",100,32.20
"IBM",50,91.10
"CAT",150,83.44
"MSFT",200,51.23
"GE",95,40.37
"MSFT",50,65.10
"IBM",100,70.44
>>> for line in filematch('Data/portfolio.csv', 'IBM'):
        print(line, end='')

"IBM",50,91.10
"IBM",100,70.44
>>>

This is kind of interesting--the idea that you can hide a bunch of custom processing in a function and use it to feed a for-loop. The next example looks at a more unusual case.

关联来源

• summaries/02_Customizing_iteration