Merge pull request #11 from LCAS/workshop_6

workshop 6 files

evaluation/iou_example.py

@@ -0,0 +1,13 @@
+from rectangle import Rectangle
+
+A = Rectangle(0, 0, 20, 20)
+B = Rectangle(10, 10, 20, 20)
+
+C = A & B # intersection rectangle
+
+print(A, A.area)
+print(B, B.area)
+print(C, C.area)
+
+print(A.iou(B)) # intersection over union
+

evaluation/rectangle.py

@@ -0,0 +1,106 @@
+from itertools import product, tee
+
+def pairwise(iterable):
+    "s -> (s0, s1), (s1, s2), (s2, s3), ..."
+    a, b = tee(iterable)
+    next(b, None)
+    return zip(a, b)
+
+class Rectangle:
+
+    __slots__ = '__x1', '__y1', '__x2', '__y2'
+
+    def __init__(self, x1, y1, x2, y2):
+        self.__setstate__((min(x1, x2), min(y1, y2), max(x1, x2), max(y1, y2)))
+
+    def __repr__(self):
+        return '{}({})'.format(type(self).__name__, ', '.join(map(repr, self)))
+
+    def __eq__(self, other):
+        return self.data == other.data
+
+    def __ne__(self, other):
+        return self.data != other.data
+
+    def __hash__(self):
+        return hash(self.data)
+
+    def __len__(self):
+        return 4
+
+    def __getitem__(self, key):
+        return self.data[key]
+
+    def __iter__(self):
+        return iter(self.data)
+
+    def __and__(self, other):
+        x1, y1, x2, y2 = max(self.x1, other.x1), max(self.y1, other.y1), \
+                         min(self.x2, other.x2), min(self.y2, other.y2)
+        if x1 < x2 and y1 < y2:
+            return type(self)(x1, y1, x2, y2)
+
+    def __sub__(self, other):
+        intersection = self & other
+        if intersection is None:
+            yield self
+        else:
+            x, y = {self.x1, self.x2}, {self.y1, self.y2}
+            if self.x1 < other.x1 < self.x2:
+                x.add(other.x1)
+            if self.y1 < other.y1 < self.y2:
+                y.add(other.y1)
+            if self.x1 < other.x2 < self.x2:
+                x.add(other.x2)
+            if self.y1 < other.y2 < self.y2:
+                y.add(other.y2)
+            for (x1, x2), (y1, y2) in product(pairwise(sorted(x)),
+                                              pairwise(sorted(y))):
+                instance = type(self)(x1, y1, x2, y2)
+                if instance != intersection:
+                    yield instance
+
+    def __getstate__(self):
+        return self.x1, self.y1, self.x2, self.y2
+
+    def __setstate__(self, state):
+        self.__x1, self.__y1, self.__x2, self.__y2 = state
+
+    @property
+    def x1(self):
+        return self.__x1
+
+    @property
+    def y1(self):
+        return self.__y1
+
+    @property
+    def x2(self):
+        return self.__x2
+
+    @property
+    def y2(self):
+        return self.__y2
+
+    @property
+    def width(self):
+        return self.x2 - self.x1
+
+    @property
+    def height(self):
+        return self.y2 - self.y1
+
+    @property
+    def area(self):
+        return self.width * self.height
+
+    def iou(self, other):
+        inter = self & other
+        return inter.area / (self.area + other.area - inter.area)  
+
+    intersection = __and__
+
+    difference = __sub__
+
+    data = property(__getstate__)
+