[英]Python default parameter if no command line arguments are passed
我想用这种行为来构建程序:
用法:鼠尾草4ct.py [-h](-r R | -i I | -p P)[-o O]
但是,如果您不提供任何参数,我希望将“ -r 100”作为默认值。
可能吗?
parser = argparse.ArgumentParser(description = '4ct args')
group_input = parser.add_mutually_exclusive_group(required = True)
group_input.add_argument("-r", "-random", help = "Random graph: dual of a triangulation of N vertices", nargs = 1, type = int, default = 100)
group_input.add_argument("-i", "-input", help = "Input edgelist filename (networkx)", nargs = 1)
group_input.add_argument("-p", "-planar", help = "Load a planar embedding of the graph G.faces() - Automatically saved at each run: input_planar_file.serialized", nargs = 1)
parser.add_argument("-o", "-output", help="Output edgelist filename (networkx)", nargs = 1, required = False)
args = parser.parse_args()
只需删除add_mutually_exclusive_group
函数调用的required
参数(或将其设置为False),就可以完成:
import argparse
parser = argparse.ArgumentParser(description = '4ct args')
group_input = parser.add_mutually_exclusive_group(required = False)
group_input.add_argument("-r", "--random", help = "Random graph: dual of a triangulation of N vertices", type = int, default = 100)
group_input.add_argument("-i", "--input", help = "Input edgelist filename (networkx)")
group_input.add_argument("-p", "--planar", help = "Load a planar embedding of the graph G.faces() - Automatically saved at each run: input_planar_file.serialized")
parser.add_argument("-o", "--output", help="Output edgelist filename (networkx)", required = False)
print(parser.parse_args())
# Namespace(input=None, output=None, planar=None, random=100)
print(parser.parse_args("-r 77".split()))
# Namespace(input=None, output=None, planar=None, random=77)
print(parser.parse_args("-o some/path".split()))
# Namespace(input=None, output='some/path', planar=None, random=100)
print(parser.parse_args("-i some/path".split()))
# Namespace(input='some/path', output=None, planar=None, random=100)
print(parser.parse_args("-i some/path -o some/other/path".split()))
# Namespace(input='some/path', output='some/other/path', planar=None, random=100)
print(parser.parse_args("-r 42 -o some/other/path".split()))
# Namespace(input=None, output='some/other/path', planar=None, random=42)
正如你所看到的, random
选项默认为即使100:
output
选项,这看起来很正常 random
之外的选项,这可能会出现问题。 您必须先检查代码是否是random
唯一具有值的独占选项,然后再考虑它。 此示例还包括对选项解析器的一些微小改进:
nargs=1
,使您可以检索一个值的列表。 通过删除它,您可以直接检索值。 尝试以下操作:
import argparse
import sys
parser = argparse.ArgumentParser(description='4ct args')
group_input = parser.add_mutually_exclusive_group(required=True)
group_input.add_argument("-r", "-random", help="Random graph: dual of a triangulation of N vertices", nargs=1, type=int, default=100)
group_input.add_argument("-i", "-input", help="Input edgelist filename (networkx)", nargs=1)
group_input.add_argument("-p", "-planar", help="Load a planar embedding of the graph G.faces() - Automatically saved at each run: input_planar_file.serialized",nargs=1)
parser.add_argument("-o", "-output", help="Output edgelist filename (networkx)", nargs=1, required=False)
if not sys.argv[1:]:
sys.argv.extend(['-r', '100'])
args = parser.parse_args(sys.argv[1:])
本质上,您正在检查是否有任何命令行参数,如果没有,则附加所需的-r 100
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.