Argparse command line passes list type parameter

Error model ( Not recommended , It is not convenient to transfer parameters dynamically ):

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--alpha', type=list, default=[0.35, 0.25, 0.40])
args = parser.parse_args()

if __name__ == '__main__':
    print(args.alpha)

Correct example 1 :

import argparse
parser = argparse.ArgumentParser()
## nargs='+' Accept 1 Two or more parameters ,
## nargs='*' Accept zero or more 
parser.add_argument('--list', nargs='+', help='<Required> Set flag', required=True)
args = parser.parse_args()

if __name__ == '__main__':
    print(args.list)

The parameters passed in at runtime are separated by spaces , The operation results are as follows :

Correct example 2 :

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--ll', action='append', help='<Required> Set flag', required=True)
args = parser.parse_args()

if __name__ == '__main__':
    print(args.ll)

Running examples and results :

reference :
https://zhuanlan.zhihu.com/p/258446208