Add lesson 13 tasks

students/bec_lukasz/lesson_13_objects_and_classes/README.md

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+### Lesson 13 - Objects and classes
+#### introduction
+- [Think Python: How to Think Like a Computer Scientist / Chapter 15](http://greenteapress.com/thinkpython2/html/thinkpython2016.html)
+- [Python dir()
+ function](https://www.programiz.com/python-programming/methods/built-in/dir)
+- [Python id() function](https://www.programiz.com/python-programming/methods/built-in/id)
+- [Python isinstance() function](https://www.programiz.com/python-programming/methods/built-in/isinstance)
+- [How To Construct Classes and Define Objects in Python 3](https://www.digitalocean.com/community/tutorials/how-to-construct-classes-and-define-objects-in-python-3) (supplementary materials)
+- [Understanding Class and Instance Variables in Python 3](https://www.digitalocean.com/community/tutorials/understanding-class-and-instance-variables-in-python-3) (supplementary materials)
+#### practice projects
+1. [Think Python: How to Think Like a Computer Scientist / Chapter 15 / Exercise 1 ](http://greenteapress.com/thinkpython2/html/thinkpython2016.html)
+1. Object inspector 1 - write a function that for a given object and list of attribute names returns dictionary with names and values of object's attributes.
+1. Object inspector 2 - write a function that for a given object returns dictionary with names and values of all object's attributes that are instances of string, integer or float.
+1. Selective shallow compare - write a function that for given 2 objects and list of attribute names checks if objects' attributes are equal.

students/bec_lukasz/lesson_13_objects_and_classes/circle.py

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+import copy
+import math
+
+
+class Point:
+    """Represents a point in 2-D space."""
+
+
+class Rectangle:
+    """Represents a rectangle.
+
+    attributes: width, height, corner.
+    """
+
+
+class Circle:
+    """Represents a circle.
+
+    Attributes: center, radius
+    """
+
+
+def print_point(p):
+    print('(%g, %g)' % (p.x, p.y))
+
+
+def find_center(rect):
+    p = Point()
+    p.x = rect.corner.x + rect.width/2
+    p.y = rect.corner.y + rect.height/2
+    return p
+
+
+def distance_between_points(first, second):
+    dx = first.x - second.x
+    dy = first.y - second.y
+    distance = math.sqrt(dx**2 + dy**2)
+    return distance
+
+
+def grow_rectangle(rect, width_arg, height_arg):
+    rect.width += width_arg
+    rect.height += height_arg
+
+
+def point_in_circle(point, circle):
+    """Checks whether a point lies inside a circle (or on the boundary).
+
+    point: Point object
+    circle: Circle object
+    """
+    d = distance_between_points(point, circle.center)
+    print(d)
+    return d <= circle.radius
+
+
+def rect_in_circle(rect, circle):
+    """Checks whether the corners of a rect fall in/on a circle.
+
+    rect: Rectangle object
+    circle: Circle object
+    """
+    p = copy.copy(rect.corner)
+    print_point(p)
+    if not point_in_circle(p, circle):
+        return False
+
+    p.x += rect.width
+    print_point(p)
+    if not point_in_circle(p, circle):
+        return False
+
+    p.y -= rect.height
+    print_point(p)
+    if not point_in_circle(p, circle):
+        return False
+
+    p.x -= rect.width
+    print_point(p)
+    if not point_in_circle(p, circle):
+        return False
+
+    return True
+
+
+def rect_circle_overlap(rect, circle):
+    """Checks whether any corners of a rect fall in/on a circle.
+
+    rect: Rectangle object
+    circle: Circle object
+    """
+    p = copy.copy(rect.corner)
+    print_point(p)
+    if point_in_circle(p, circle):
+        return True
+
+    p.x += rect.width
+    print_point(p)
+    if point_in_circle(p, circle):
+        return True
+
+    p.y -= rect.height
+    print_point(p)
+    if point_in_circle(p, circle):
+        return True
+
+    p.x -= rect.width
+    print_point(p)
+    if point_in_circle(p, circle):
+        return True
+
+    return False
+
+
+def main():
+    box = Rectangle()
+    box.width = 100.0
+    box.height = 200.0
+    box.corner = Point()
+    box.corner.x = 50.0
+    box.corner.y = 50.0
+
+    print(box.corner.x)
+    print(box.corner.y)
+
+    circle = Circle
+    circle.center = Point()
+    circle.center.x = 150.0
+    circle.center.y = 100.0
+    circle.radius = 75.0
+
+    print(circle.center.x)
+    print(circle.center.y)
+    print(circle.radius)
+
+    print(point_in_circle(box.corner, circle))
+    print(rect_in_circle(box, circle))
+    print(rect_circle_overlap(box, circle))
+
+
+if __name__ == '__main__':
+    main()

students/bec_lukasz/lesson_13_objects_and_classes/object_inspector_1.py

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+class Point:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+
+def object_inspector(obj, attributes):
+    dictionary = {}
+    for attribute in attributes:
+        value = getattr(obj, attribute)
+        dictionary[attribute] = value
+    return dictionary
+
+
+def main():
+    point = Point(10, 20)
+    print(object_inspector(point, ['x', 'y']))
+
+
+if __name__ == '__main__':
+    main()

students/bec_lukasz/lesson_13_objects_and_classes/object_inspector_2.py

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+class Point:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+
+class Sth:
+    def __init__(self, v, x, y, z):
+        self.v = v
+        self.x = x
+        self.y = y
+        self.z = z
+
+
+def object_inspector2(obj):
+    attributes = dir(obj)
+    dictionary = {}
+    for i in attributes:
+        if isinstance(getattr(obj, i), (int, float, str)):
+            value = getattr(obj, i)
+            dictionary[i] = value
+    return dictionary
+
+
+def main():
+    point = Point(10, 20)
+    sth = Sth(point, 10, 20.0, 'trzydziesci')
+    print(object_inspector2(sth))
+
+
+if __name__ == '__main__':
+    main()

students/bec_lukasz/lesson_13_objects_and_classes/shallow.py

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+class Sth:
+    def __init__(self, x, y, z):
+        self.x = x
+        self.y = y
+        self.z = z
+
+
+def shallow(object_one, object_two, attributes):
+    for attr in attributes:
+
+        if getattr(object_one, attr) != getattr(object_two, attr):
+            print('Not equal')
+        else:
+            print('Equal')
+
+
+def main():
+    first = Sth(10, 10.0, 'first')
+    second = Sth(10, 10.0, 'first')
+    third = Sth(10, 10.0, 'third')
+    attrs = ['x', 'y', 'z']
+    shallow(first, second, attrs)
+    shallow(first, third, attrs)
+
+
+if __name__ == '__main__':
+    main()