sort list of objects by method-CodePudding

I am trying to sort a list of class Shape.the shape class has a method surface() which return an int. How would I sort this list from biggest to smallest surface

The code is this

def sort_list(list_shapes):
    '''
        for shape in list_shapes:
            shape.surface() = int
        
        output = list_shapes sorted by surface size
    '''
    pass

# for context: Shape Class
class Shape:
    def __init__(self, width, height):
        self.width = width
        self.height = height

    def surface(self):
        surface = float(self.width * self.height)
        return round(surface, 2)

I've tried with sort and sorted but cant seem to make it work. I believe possibly I could do something like list(map()) but also couldn't figure it out.

Would love to get a better understanding on which way is best for this

CodePudding user response：

You can use built-in sorted() function __ge__() / __lt__() magic methods.

Here is an example:

class Shape:
    def __init__(self, width, height):
        self.width = width
        self.height = height

    def __ge__(self, other: 'Shape'):
        return self.surface() > other.surface()

    def __lt__(self, other: 'Shape'):
        return self.surface() < other.surface()

    def __repr__(self):
        # return surface - just for print() demo
        return str(self.surface())

    def surface(self):
        surface = float(self.width * self.height)
        return round(surface, 2)


shapes = [
    Shape(2, 2),
    Shape(3, 3),
    Shape(1, 2),
    Shape(1, 1),
    Shape(5, 5),
    Shape(2, 1),
    Shape(1, 1),
    Shape(2, 2),
]

print(sorted(shapes))  # [1.0, 1.0, 2.0, 2.0, 4.0, 4.0, 9.0, 25.0]

CodePudding user response：

def sort_list(list_shapes):
    return sorted(list_shapes, key = lambda x: x.surface())