Python 中argparse模块的使用

import sys
print("输入的参数为:%s" % sys.argv[1])

>python demo.py 1
输入的参数为:1

import argparse
# description参数可以用于描述脚本的参数作用，默认为空
parser=argparse.ArgumentParser(description="A description of what the program does")
parser.add_argument('--toy','-t',action='store_true',help='Use only 50K samples of data')
parser.add_argument('--num_epochs',choices=[5,10,20],default=5,type=int,help='Number of epochs.')
parser.add_argument("--num_layers", type=int, required=True, help="Network depth.")

args=parser.parse_args()
print(args)
print(args.toy,args.num_epochs,args.num_layers)

>python demo.py --num_epochs 10 --num_layers 10
Namespace(num_epochs=10, num_layers=10, toy=False)
False 10 10

parser.add_argument('--toy','-t',action='store_true',help='Use only 50K samples of data')

>python demo.py -t --num_epochs 10 --num_layers 10
Namespace(num_epochs=10, num_layers=10, toy=True)
True 10 10 # 对比和上次执行的区别

parser.add_argument('--num_epochs',choices=[5,10,20],default=5,type=int,help='Number of epochs.')

>python demo.py -t --num_epochs 30 --num_layers 10
usage: demo.py [-h] [--toy] [--num_epochs {5,10,20}] --num_layers NUM_LAYERS
demo.py: error: argument --num_epochs: invalid choice: 30 (choose from 5, 10, 20)

>python demo.py -t  --num_layers 10
Namespace(num_epochs=5, num_layers=10, toy=True)
True 5 10

parser.add_argument("--num_layers", type=int, required=True, help="Network depth.")

>python demo.py -t --num_epochs 10
usage: demo.py [-h] [--toy] [--num_epochs {5,10,20}] --num_layers NUM_LAYERS
demo.py: error: the following arguments are required: --num_layers

>python demo.py -h
usage: demo.py [-h] [--toy] [--num_epochs {5,10,20}] --num_layers NUM_LAYERS

A description of what the program does

optional arguments:
  -h, --help            show this help message and exit
  --toy, -t             Use only 50K samples of data
  --num_epochs {5,10,20}
                        Number of epochs.
  --num_layers NUM_LAYERS
                        Network depth.