Work in Spyder!
Shapes on a canvas
Write a class called Shape.
- Let it have two members: x and y, the coordinates of the shape on the plane (center of mass).
- Define a move method, with one parameter v: a list of length 2, a vector to translate the shape with. After this method the coordinates should be changed.
Define the following classes as children of Shape:
- Ellipse with additional parameters (except the (x, y) coordinates): a and b the x and y axes radii
- Rectangle with additional parameters (except the (x, y) coordinates) a and b the length of the sides
Write an area method for both, which calculates the area!
Define an equation method for printing the equation of the Ellipse! Something like:
((x-1)/2)^2 + ((y-2)/3)^2 = 1
Inheritance and constructors
If the child class (e.g. Ellipse) you want to call the parents class' constructor then you have two ways:
class B(A): def __init__(self, x, y, a, b): A.__init__(self, x, y) # OR super(B, self).__init__(x, y)
The first explicitly calls the parents __init__
A.__init__(self, x, y)
The second one calls the parent of B which happens to be A:
super(B, self).__init__(x, y)
Define a class called Canvas (vászon)
- Its only member variable should be a list of Shapes: shapes. This stores several Shape objects.
- Define an add method which adds a new shape to the canvas!
- Make this class iterable! Write the __iter__(self) and the next(self) methods, as seen on the lecture.
- Define a crop method in the following way.
- Its two parameters should be two coordinates: a top-left corner and a bottom-right corner.
- The function should return the list of Shapes which entirely fit in that rectangle.
- For this it is best to implement a box() method on both Ellipse and Rectangle which returns a bounding box of the shape:
a list of two coordinates, the top-left corner and a bottom-right corner of the object.
Write an iterable class like range, but without returning a whole list, but storing only the actual element.
class Range(object): def __init__( ... ): ... def __iter__( ... ): ... def next( ... ): ...
- Its constructor should have one parameter: a number or a string. The iteration should go up that number, from 0 with 1 steps.
- If the number is not positive, then the iteration should take 0 steps.
- If you get a string then try to convert it to a number. It it cannot be converted, then raise a ValueError exception.
- If it is a valid integer, then calculate with that.
- If you get the string "inf" then make the iteration go endless (infinite loop)!