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python_note

seanbefore edited this page Mar 16, 2018 · 3 revisions

Python 零碎笔记

2 argparse

用于解析命令行参数和选项,用来代替optparse模块,例:

python parseTest.py input.txt output.txt --user=name --port=8080。

使用方法:

1.import argparse
2.parser = argparse.ArgumentParser()
3.parser.add_argument(
 '--learning_rate',
 type=float,
 default=0.01,
 help='Initial learning rate.'
)
4.FLAGS, unparsed = parser.parse_known_args()
 print FLAGS.learning_rate

1 python assert断言的作用

python assert断言是声明其布尔值必须为真的判定,如果发生异常就说明表达示为假。可以理解assert断言语句为raise-if-not,用来测试表示式,其返回值为假,就会触发异常。

assert 1==1
assert 2+2==2*2
assert len(['my boy',12])<10
assert range(4)==[0,1,2,3] 

添加异常参数

assert expression [, arguments]
assert 表达式 [, 参数]
assert len(lists) >=5,'列表元素个数小于5'
assert 2==1,'2不等于1'

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