How do I create class instances using values from a list of dicts in Python?

Question

I have the following class setup:

class Card(object):
    def __init__(self, name="", attack=0, defense=0, magic=0, shield=0, description=""):
        self.name = name
        self.attack = int(attack)
        self.defense = int(defense)
        self.magic = int(magic)
        self.shield = int(shield)
        self.description = description

I would like to make instances of Card using a list of dictionaries created from csv.dictreader.

Here is what the method for determining my cardList returns:

[
{'Magic': '200', 'Shield': '100', 'NameOfCard': 'Knight', 'Attack': '700', 'Defense': '400', 'Description': ''},
{'Magic': '500', 'Shield': '500', 'NameOfCard': 'Mage', 'Attack': '0', 'Defense': '0', 'Description': ''},
{'Magic': '100', 'Shield': '100', 'NameOfCard': 'Peasant', 'Attack': '100', 'Defense': '100', 'Description': ''},
{'Magic': '0', 'Shield': '0', 'NameOfCard': 'Lancer', 'Attack': '400', 'Defense': '100', 'Description': ''},
{'Magic': '100', 'Shield': '200', 'NameOfCard': 'Guardian', 'Attack': '100', 'Defense': '600', 'Description': ''},
...]

I was hoping to be able to use the 'NameOfCard' values to name the instances, and then map the values to the arguments taken by the __init__ method in the Card class.

My first thought was to do something like this:

Knight = Card(cardList[0]('NameOfCard')...)

But calling print Knight.name returns TypeError: 'dict' object is not callable.

How do I use my list of dicts to create instances of the Card class?

Blender · Accepted Answer · 2013-05-29 16:23:55Z

3

Use argument unpacking:

knight = Card(**dict_of_properties)

This will expand dict_of_properties into named arguments:

knight = Card(name='foo', stuff='bar')

Assuming dict_of_properties looks like:

dict_of_properties = {
    'name': 'foo',
    'stuff': 'bar'
}

answered May 29, 2013 at 16:23

Blender

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1 Comment

bhamhawker Over a year ago

Thanks! This worked, just like the above answer too. I did not know about the ** ability.

Ignacio Vazquez-Abrams · Accepted Answer · 2013-05-29 16:23:18Z

2

If the argument names were the same as the dict keys then you could use:

Knight = Card(**cardList[0])

As it is you'll need to map the dict keys to the proper argument names first.

answered May 29, 2013 at 16:23

Ignacio Vazquez-Abrams

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1 Comment

bhamhawker Over a year ago

I reworked the csv file to make the keys match. Thanks! I did not know about the ** ability.

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