将 argparse 与采用 **kwargs 参数的函数一起使用 [英] Using argparse with function that takes **kwargs argument
问题描述
我正在使用 argparse
获取输入并将其传递给一个函数,该函数将两个变量和 **kwargs
作为参数.
这是我的功能:
导入请求导入系统导入参数解析def location_by_coordinate(LAT, LNG, **kwargs):如果不是 kwargs:坐标网址 = "https://api.instagram.com/v1/locations/search?lat=%s&lng=%s&access_token=%s" % (LAT, LNG, current_token)r = requests.get(coordinate_url).text别的:坐标网址 = "https://api.instagram.com/v1/locations/search?lat=%s&lng=%s&access_token=%s" % (LAT, LNG, current_token)对于键,kwargs.iteritems() 中的值:如果以 kwargs 为单位的距离":距离 = kwargs.get('DISTANCE')如果距离>5000:打印距离打印最大距离为 5000 米,值重新分配为默认值 1000 米"距离 = 1000坐标网址 = "https://api.instagram.com/v1/locations/search?lat=%s&lng=%s&access_token=%s" % (LAT, LNG, current_token)r = requests.get(coordinate_url).text别的:经过坐标网址 = "https://api.instagram.com/v1/locations/search?lat=%s&lng=%s&access_token=%s" % (LAT, LNG, current_token)r = requests.get(coordinate_url).text如果 kwargs 中的FACEBOOK_PLACES_ID":fb_places_id = kwargs.get('FACEBOOK_PLACES_ID')有效载荷 = {'FACEBOOK_PLACES_ID': '%s' % (fb_places_id), 'DISTANCE': '%s' % (DISTANCE)}r = requests.get(coordinate_url, params=payload).text如果 kwargs 中的FOURSQUARE_ID":Foursquare_id = kwargs.get('FOURSQUARE_ID')有效载荷 = {'FOURSQUARE_ID': '%s' % (foursquare_id), 'DISTANCE': '%s' % (DISTANCE)}r = requests.get(coordinate_url, params=payload).text如果 kwargs 中的FOURSQUARE_V2_ID":Foursquare_v2_id = kwargs.get('FOURSQUARE_V2_ID')有效载荷 = {'FOURSQUARE_V2_ID': '%s' % (foursquare_v2_id), 'DISTANCE': '%s' % (DISTANCE)}r = requests.get(coordinate_url, params=payload).text#打印r返回
鉴于此函数及其对 **kwargs 的使用,我应该如何设置子解析器?
到目前为止,我是这样设置命令行解析器的:
def main():parser = argparse.ArgumentParser(description="API Endpoints tester")subparsers = parser.add_subparsers(dest="command", help="可用命令")location_by_parser = subparsers.add_parser("location_by_coordinate", help="位置函数")location_by_parser.add_argument("LAT", help="纬度")location_by_parser.add_argument("LNG", help="longitude")参数 = parser.parse_args(sys.argv[1:])参数 = vars(参数)命令 = arguments.pop("命令")如果命令==location_by_coordinate":LAT, LNG = location_by_coordinate(**参数)别的:打印未提供命令..."如果 __name__ == "__main__":主要的()
显然,当我像这样在命令行中调用上面的 main() 函数时,它与 location_by_coordinate() 函数配合得很好:
$ python argstest.py location_by_coordinate 40.5949799 -73.9495148
但是使用当前的代码,如果我尝试:
$ python argstest.py location_by_coordinate 40.5949799 -73.9495148 DISTANCE=3000
显然,我得到:
argstest.py:错误:无法识别的参数:DISTANCE=3000
但我不确定如何为 **kwargs 设置子解析器.如果我尝试设置这样的子解析器:
location_by_parser.add_argument("**kwargs", help="**kwargs")
然后再次尝试该命令:
$ python argstest.py location_by_coordinate 40.5949799 -73.9495148 DISTANCE=3000
这不起作用,因为 arguments
对象(它是一个字典)变成了这样:
{'LAT':'40.5949799','LNG':'-73.9495148','command':'location_by_coordinate','**kwargs':'DISTANCE=3000'
}>
返回此回溯:
回溯(最近一次调用最后一次): 中的文件argstest.py",第 118 行主要的()文件argstest.py",第 108 行,在主目录中foo = location_by_coordinate(**参数)文件argstest.py",第 40 行,位于 location_by_coordinate返回UnboundLocalError:赋值前引用了局部变量r"
如何启用 argparse 来处理/解析在命令行中输入的内容,这些内容旨在通过 **kwargs 传递给函数?
你了解
{'LAT': '40.5949799', 'LNG': '-73.9495148', 'command': 'location_by_coordinate', '**kwargs': 'DISTANCE=3000'}
arguments
字典?您使用 '**kwargs' 的名称 ('dest') 定义了一个 'positional' 参数.您也可以将其命名为foobar".解析器将字符串 'DISTANCE=3000' 分配给 args
命名空间中的该属性,该属性在 arguments
中变成了字典键:值对.
当然,您可以查找 arguments['**kwargs']
,然后自己解析该值:
v = arguments['**kwargs'] # 如果你愿意,也可以弹出如果 v 不是 None:k, v = v.split('=')参数[k] = int(v)
可以概括为处理多个对(用 `nargs='*' 定义).
<小时>argparse
不像 Python 函数那样处理参数,所以没有什么与 **kwargs
完全类似.
接受诸如 distance
之类的东西的正常方法是使用可选"或标记参数.
parser.add_argument('-d','--distance', type=int, help=...)
哪个会接受
python argstest.py location_by_coordinate 40.5949799 -73.9495148 --distance=3000python argstest.py location_by_coordinate 40.5949799 -73.9495148 --distance 3000python argstest.py location_by_coordinate 40.5949799 -73.9495148 --d3000python argstest.py location_by_coordinate 40.5949799 -73.9495148
也可以设置为使用 --DISTANCE
或其他名称.在最后一种情况下,args
命名空间将具有 distance
的默认值.默认默认值为 None
.
这是将 kwarg
之类的参数添加到 argparse
的直接方法.
接受像对这样的任意字典,distance:3000
,distance=3000
,之前已经在SO上被问过.答案一直是我在上面勾画的解析的一些变体.它可以在自定义 Action 类中完成,也可以按照我的建议进行解析.
哎呀,这个答案几乎是我几天前写的一个答案的克隆:https://stackoverflow.com/a/33639147/901925
一个类似的 2011 年问题:使用argparse解析arg=val"形式的参数
==================================
(编辑)
使用 *args
的函数示例:
在[2]中:导入argparse在 [3]: def foo(*args, **kwargs):...:打印('args',args)...:打印('kwargs',kwargs)...:在 [4]: parser=argparse.ArgumentParser()在 [5] 中:parser.add_argument('arg1')在 [6]: parser.add_argument('arg2',nargs='+')在[7]中:args=parser.parse_args('一二三'.split())在 [8] 中:参数Out[8]: Namespace(arg1='one', arg2=['two', 'three'])
所以我有 2 个位置参数,一个带有单个字符串值,另一个带有列表(由于 +
nargs).
使用这些 args
属性调用 foo
:
在 [10]: foo(args.arg1)args ('一个',)夸格{}在 [11]: foo(args.arg1, args.arg2)args ('一', ['二', '三'])夸格{}在 [12]: foo(args.arg1, arg2=args.arg2)args ('一个',)kwargs {'arg2': ['二', '三']}
我定义了位置",但它与可选"一样有效.位置和可选之间的区别在命名空间中消失了.
如果我将命名空间转换为字典,我可以通过各种方式将值传递给 foo
,通过 *args
或通过 **kwargs代码>.这完全取决于我如何调用
foo
,而不是它们如何出现在 args
或 arguments
中.这些都不是 argparse
独有的.
在[13]中:arguments = vars(args)在 [14] 中:参数出[14]:{'arg2':['二','三'],'arg1':'一'}在 [15]: foo(arguments['arg2'],arguments['arg1'])args (['二', '三'], '一')夸格{}在 [16]: foo(arguments['arg2'],arguments)args (['二', '三'], {'arg2': ['二', '三'], 'arg1': '一'})夸格{}在 [17]: foo(arguments['arg2'], **arguments)args (['二', '三'],)kwargs {'arg2':['二','三'],'arg1':'一'}在 [24]: foo(*arguments, **arguments)args('arg2', 'arg1') # *args 是参数的键kwargs {'arg2':['二','三'],'arg1':'一'}在 [25]: foo(*arguments.values(), **arguments)args (['two', 'three'], 'one') # *args 是参数的值kwargs {'arg2':['二','三'],'arg1':'一'}
I'm using argparse
to take input and pass it to a function that takes as arguments two variables and **kwargs
.
Here's my function:
import requests
import sys
import argparse
def location_by_coordinate(LAT, LNG, **kwargs):
if not kwargs:
coordinate_url = "https://api.instagram.com/v1/locations/search?lat=%s&lng=%s&access_token=%s" % (LAT, LNG, current_token)
r = requests.get(coordinate_url).text
else:
coordinate_url = "https://api.instagram.com/v1/locations/search?lat=%s&lng=%s&access_token=%s" % (LAT, LNG, current_token)
for key, value in kwargs.iteritems():
if 'DISTANCE' in kwargs:
distance = kwargs.get('DISTANCE')
if distance > 5000:
print distance
print "max distance is 5000m, value is reassigned to default of 1000m"
distance = 1000
coordinate_url = "https://api.instagram.com/v1/locations/search?lat=%s&lng=%s&access_token=%s" % (LAT, LNG, current_token)
r = requests.get(coordinate_url).text
else:
pass
coordinate_url = "https://api.instagram.com/v1/locations/search?lat=%s&lng=%s&access_token=%s" % (LAT, LNG, current_token)
r = requests.get(coordinate_url).text
if 'FACEBOOK_PLACES_ID' in kwargs:
fb_places_id = kwargs.get('FACEBOOK_PLACES_ID')
payload = {'FACEBOOK_PLACES_ID': '%s' % (fb_places_id), 'DISTANCE': '%s' % (DISTANCE)}
r = requests.get(coordinate_url, params=payload).text
if 'FOURSQUARE_ID' in kwargs:
foursquare_id = kwargs.get('FOURSQUARE_ID')
payload = {'FOURSQUARE_ID': '%s' % (foursquare_id), 'DISTANCE': '%s' % (DISTANCE)}
r = requests.get(coordinate_url, params=payload).text
if 'FOURSQUARE_V2_ID' in kwargs:
foursquare_v2_id = kwargs.get('FOURSQUARE_V2_ID')
payload = {'FOURSQUARE_V2_ID': '%s' % (foursquare_v2_id), 'DISTANCE': '%s' % (DISTANCE)}
r = requests.get(coordinate_url, params=payload).text
#print r
return r
Given this function and its use of **kwargs, how should I setup the subparsers?
Here's how I've setup the command line parser thus far:
def main():
parser = argparse.ArgumentParser(description="API Endpoints tester")
subparsers = parser.add_subparsers(dest="command", help="Available commands")
location_by_parser = subparsers.add_parser("location_by_coordinate", help="location function")
location_by_parser.add_argument("LAT", help="latitude")
location_by_parser.add_argument("LNG", help="longitude")
arguments = parser.parse_args(sys.argv[1:])
arguments = vars(arguments)
command = arguments.pop("command")
if command == "location_by_coordinate":
LAT, LNG = location_by_coordinate(**arguments)
else:
print "No command provided..."
if __name__ == "__main__":
main()
Obviously, the above main() function works fine with the location_by_coordinate() function when I call it at the command line like this:
$ python argstest.py location_by_coordinate 40.5949799 -73.9495148
But with the code the way it is currently, if I try:
$ python argstest.py location_by_coordinate 40.5949799 -73.9495148 DISTANCE=3000
Obviously, I get:
argstest.py: error: unrecognized arguments: DISTANCE=3000
But I'm not sure how to setup a subparser for **kwargs. If I try to setup a subparser like this:
location_by_parser.add_argument("**kwargs", help="**kwargs")
and then try that command again:
$ python argstest.py location_by_coordinate 40.5949799 -73.9495148 DISTANCE=3000
That doesn't work because the arguments
object (which is a dictionary), becomes this:
{'LAT': '40.5949799', 'LNG': '-73.9495148', 'command': 'location_by_coordinate', '**kwargs': 'DISTANCE=3000'
}
And this Traceback is returned:
Traceback (most recent call last):
File "argstest.py", line 118, in <module>
main()
File "argstest.py", line 108, in main
foo = location_by_coordinate(**arguments)
File "argstest.py", line 40, in location_by_coordinate
return r
UnboundLocalError: local variable 'r' referenced before assignment
How can I enable argparse to handle/to parse what is entered at the command line that is intended to be passed to the function via **kwargs?
Do you understand what is going on with the
{'LAT': '40.5949799', 'LNG': '-73.9495148', 'command': 'location_by_coordinate', '**kwargs': 'DISTANCE=3000'}
arguments
dictionary? You defined a 'positional' argument with the name ('dest') of '**kwargs'. You could just as well named it 'foobar'. The parser assigned the string 'DISTANCE=3000' to that attribute in the args
namespace, which turned into a dictionary key:value pair in arguments
.
You could, of course, look for arguments['**kwargs']
, and parse the value for yourself:
v = arguments['**kwargs'] # or pop if you prefer
if v is not None:
k, v = v.split('=')
arguments[k] = int(v)
It could be generalized to handle multiple pairs (defined with `nargs='*').
argparse
does not handle arguments the same way as Python functions, so there's nothing exactly analogous the **kwargs
.
The normal way to accept something like distance
is with 'optionals' or flagged arguments.
parser.add_argument('-d','--distance', type=int, help=...)
which will accept
python argstest.py location_by_coordinate 40.5949799 -73.9495148 --distance=3000
python argstest.py location_by_coordinate 40.5949799 -73.9495148 --distance 3000
python argstest.py location_by_coordinate 40.5949799 -73.9495148 --d3000
python argstest.py location_by_coordinate 40.5949799 -73.9495148
It could also be setup to use --DISTANCE
or other names. In the last case args
namespace will have a default value for distance
. The default default is None
.
That's the straight forward way of adding kwarg
like arguments to argparse
.
Accepting arbitrary dictionary like pairs, distance:3000
, distance=3000
, has been asked before on SO. The answers have always been some variation of the parsing that I sketched above. It could be done in a custom Action class, or post parsing as I suggest.
oops, this answer is nearly a clone of one I wrote a few days ago: https://stackoverflow.com/a/33639147/901925
A similar 2011 question: Using argparse to parse arguments of form "arg= val"
=================================
(edit)
Example with a function that takes *args
:
In [2]: import argparse
In [3]: def foo(*args, **kwargs):
...: print('args',args)
...: print('kwargs',kwargs)
...:
In [4]: parser=argparse.ArgumentParser()
In [5]: parser.add_argument('arg1')
In [6]: parser.add_argument('arg2',nargs='+')
In [7]: args=parser.parse_args('one two three'.split())
In [8]: args
Out[8]: Namespace(arg1='one', arg2=['two', 'three'])
So I have 2 positional arguments, one with a single string value, the other with a list (due to the +
nargs).
Call foo
with these args
attributes:
In [10]: foo(args.arg1)
args ('one',)
kwargs {}
In [11]: foo(args.arg1, args.arg2)
args ('one', ['two', 'three'])
kwargs {}
In [12]: foo(args.arg1, arg2=args.arg2)
args ('one',)
kwargs {'arg2': ['two', 'three']}
I defined 'positionals', but it would have worked just as well with 'optionals'. The distinction between positionals and optionals disappears in the namespace.
If I convert the namespace to a dictionary, I can pass values to foo
in various ways, either through the *args
or through **kwargs
. It's all in how I call foo
, not in how they appear in args
or arguments
. None of this is unique to argparse
.
In [13]: arguments = vars(args)
In [14]: arguments
Out[14]: {'arg2': ['two', 'three'], 'arg1': 'one'}
In [15]: foo(arguments['arg2'], arguments['arg1'])
args (['two', 'three'], 'one')
kwargs {}
In [16]: foo(arguments['arg2'], arguments)
args (['two', 'three'], {'arg2': ['two', 'three'], 'arg1': 'one'})
kwargs {}
In [17]: foo(arguments['arg2'], **arguments)
args (['two', 'three'],)
kwargs {'arg2': ['two', 'three'], 'arg1': 'one'}
In [24]: foo(*arguments, **arguments)
args ('arg2', 'arg1') # *args is the keys of arguments
kwargs {'arg2': ['two', 'three'], 'arg1': 'one'}
In [25]: foo(*arguments.values(), **arguments)
args (['two', 'three'], 'one') # *args is the values of arguments
kwargs {'arg2': ['two', 'three'], 'arg1': 'one'}
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