Merge pull request #521 from realpython/python-sequences

python-sequences

Author: brendaweles

python-sequences/README.md

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+# Python Sequences: A Comprehensive Guide
+
+This folder contains source code for the Real Python tutorial [Python Sequences: A Comprehensive Guide](https://realpython.com/python-sequences-comprehensive-guide/).
+
+For more code, intermediate steps, and additional explanation, check out the associated tutorial.

python-sequences/draw_shape.py

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+import turtle
+
+from shape import ShapePoints
+
+triangle = ShapePoints([(100, 100), (-200, 100), (-200, -200)])
+
+# Draw the shape using turtle graphics
+turtle.penup()
+# Move to the first point
+turtle.setposition(triangle[0])
+turtle.pendown()
+# Draw lines to the other points
+for point in triangle[1:]:
+    turtle.setposition(point)
+
+turtle.done()

python-sequences/shape.py

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+class ShapePoints:
+    """
+    A ShapePoints object represents a collection of points
+
+    Attributes:
+    - points: sequence of points, where each point is a
+        tuple (x, y)
+    """
+
+    def __init__(self, points):
+        self.points = list(points)
+        if points and self.points[0] != self.points[-1]:
+            self.points.append(self.points[0])
+
+    def __repr__(self):
+        return f"ShapePoints({self.points})"
+
+    def __getitem__(self, index):
+        return self.points[index]
+
+    def __len__(self):
+        if self.points:
+            return len(self.points) - 1
+        return 0
+
+    def __iter__(self):
+        return iter(self.points)

python-sequences/shape_abc.py

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+from collections.abc import MutableSequence
+
+
+class ShapePoints(MutableSequence):
+    MIN_POINTS = 3
+
+    def __init__(self, points):
+        self.points = list(points)
+        if len(self.points) < self.MIN_POINTS:
+            raise ValueError(
+                f"Shape must have at least {self.MIN_POINTS} points"
+            )
+        if points and self.points[0] != self.points[-1]:
+            self.points.append(self.points[0])
+
+    def __repr__(self):
+        return f"ShapePoints({self.points})"
+
+    def __getitem__(self, index):
+        return self.points[index]
+
+    def __len__(self):
+        if self.points:
+            return len(self.points) - 1
+        return 0
+
+    def __iter__(self):
+        return iter(self.points)
+
+    def __contains__(self, item):
+        print("Checking if item is in ShapePoints")
+        return item in self.points
+
+    def __delitem__(self, index):
+        if len(self) < self.MIN_POINTS + 1:
+            raise ValueError(
+                f"Shape must have at least {self.MIN_POINTS} points"
+            )
+        if index in (0, len(self.points) - 1, -1):
+            del self.points[0]
+            self.points[-1] = self.points[0]
+        else:
+            del self.points[index]
+
+    def __setitem__(self, index, value):
+        if index in (0, len(self.points) - 1, -1):
+            self.points[0] = value
+            self.points[-1] = value
+        else:
+            self.points[index] = value
+
+    def insert(self, index, value):
+        if index in (0, len(self.points) - 1, -1):
+            self.points.insert(0, value)
+            self.points[-1] = value
+        else:
+            self.points.insert(index, value)
+
+    def count(self, value):
+        return self.points[:-1].count(value)
+
+    def append(self, value):
+        self.points.append(self.points[0])
+        self.points[-2] = value