Creating a python Rectangle object class that can print the corner coordinates

问题

I am new to python. I need to create a python Rectangle object class that when called upon one can print the coordinates of the corners as well as have the area and perimeter. I am having issues when I try to run my code that says:

<__main__.Rectangle instance at 0x02F20030>

I was told to add the __str__ as well but then I get:

TypeError: __str__ returned non-string (type int)

Any help would be appreciated, thanks!

class Rectangle:
    def __init__(self, topLeft, topRight, bottomLeft, bottomRight):
        self.tL = topLeft
        self.tR = topRight
        self.bL = bottomLeft
        self.bR = bottomRight
    def perim(self):
            return (2 * (self.tL + self.tR)) + (2 * (self.bL + self.bR))
    def area(self):
            return (self.tL + self.tR) * (self.bL + self.bR)
    def position(self):
        return self.tL
        return self.tR
        return self.bL
        return self.bR
def __repr__(self):
        return self.tL
        return self.tR
        return self.bL
        return self.bT


r1 = Rectangle (5, 5, 10, 10)
print r1

回答1:

try this:

    def __repr__(self):
        return 'tL = '+str(self.tL) + ', tR ='+ str(self.tR)+', bL ='+ str(self.bL) + ', bR =' +str(self.bR)

notes:

make only one return statement execute in a function, in your code your function only returns self.bT (the last).
In the provided code def __repr__(self) is not indented.
you don't need 4 points to define a rectangle.
your Rectangle corners shouldn't just be integers, they have to be sequences of two coordinates (x, y) for instance (3, 7) is a point, implement a point as a 2 integers tuple or list.

edit: as the OP asked, here's how to change your __init__ method to work with cartesian coordinates:

class Rectangle:
    def __init__(self, tL, bR):  #tL and bR should be passed as tuples
        self.tL = tL
        self.tR = (bR[0], tL[1])  #access tuple elements with tuple[index]
        self.bL = (bR[1], tL[0])
        self.bR = bR

        self.width = bR[0]- tL[0]
        self.height = bR[1] - tL[1]
    def area(self):
        #get area
        #...
    def perim(self):
        #get perim
        #...

r1 = Rectangle((5,5), (30, 20))
print r1.tL   #output (5, 5)
print r1.tR   #output (30, 5)
print r1.width #output 25
print r1.area() #output 375

of course you can create a Point class instead of that, and then you pass two Points to __init__ to define the rectangle.

I hope that helped you!

回答2:

First of all, functions cannot have more than one return statement.

Also, def __repr__(self): is not correctly indented (it belongs to the Rectangle class).

You might prefer __str__ over __repr__, see https://docs.python.org/2/reference/datamodel.html#object.repr for more details.

class Rectangle:
    def __init__(self, topLeft, topRight, bottomLeft, bottomRight):
        self.tL = topLeft
        self.tR = topRight
        self.bL = bottomLeft
        self.bR = bottomRight
    def perim(self):
        return (2 * (self.tL + self.tR)) + (2 * (self.bL + self.bR))
    def area(self):
        return (self.tL + self.tR) * (self.bL + self.bR)
    def position(self):
        return (self.tL, self.tR, self.bL, self.bR)
    def __str__(self):
        return "Rectangle(%s, %s, %s, %s)" % (self.tL, self.tR, self.bL, self.bR)

r1 = Rectangle (5, 5, 10, 10)
print r1
print "Perimeter: %s" % r1.perim()
print "Area: %s" % r1.area()
print "Position: (%s, %s, %s, %s)" % r1.position()

来源：https://stackoverflow.com/questions/36362455/creating-a-python-rectangle-object-class-that-can-print-the-corner-coordinates

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