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I want to build a query for sunburnt (solr interface) using class inheritance and therefore adding key-value pairs together. The sunburnt interface takes keyword arguments. How can I transform a dict ({'type':'Event'}) into keyword arguments (type='Event')?

wjandrea
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teaforthecat
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3 Answers3

816

Use the double-star (aka double-splat?) operator:

func(**{'type':'Event'})

is equivalent to

func(type='Event')
Community
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unutbu
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    and if you already have a dict object called "myDict" you just `func(**myDict)` .i.e `myDict = {"type": "event"}` – James Khoury Apr 19 '11 at 00:57
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    This is pretty well-covered in the python standard documentation. See also: http://stackoverflow.com/questions/1137161. (dmid://juice_cobra_hush) – dreftymac Feb 29 '16 at 23:17
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    This is brilliantly helpful, especially when using converting dictionaries into Swagger model instances. Thanks. – timmins Feb 21 '19 at 22:59
45

** operator would be helpful here.

** operator will unpack the dict elements and thus **{'type':'Event'} would be treated as type='Event'

func(**{'type':'Event'}) is same as func(type='Event') i.e the dict elements would be converted to the keyword arguments.

FYI

* will unpack the list elements and they would be treated as positional arguments.

func(*['one', 'two']) is same as func('one', 'two')

Vishvajit Pathak
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17

Here is a complete example showing how to use the ** operator to pass values from a dictionary as keyword arguments.

>>> def f(x=2):
...     print(x)
... 
>>> new_x = {'x': 4}
>>> f()        #    default value x=2
2
>>> f(x=3)     #   explicit value x=3
3
>>> f(**new_x) # dictionary value x=4 
4
Ben Mares
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