#!/usr/bin/env python
# coding: utf-8

# In[10]:


# Procedural approach
import math
def perimeter(polygon):
    """Given a list of vector vertices (in proper order), 
    returns the perimeter for the associated polygon."""
    total = 0
    for i in range(len(polygon)):
        vertex1 = polygon[i]
        vertex2 = polygon[(i+1) % len(polygon)]
        distance = math.sqrt((vertex2[0] - vertex1[0]) ** 2
                             + (vertex2[1] - vertex1[1]) ** 2)
        total += distance
    return total


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perimeter([[0, 0], [1, 0], [1, 1], [0, 1]]) # a square with sides of length 1


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vertices = [[0, -2], [1, 1], [3, 3], [5, 1], [4, 0], [4, -3]]
perimeter(vertices) # a more complex shape


# In[20]:


# just for illustration, let's see what this polygon looks like
get_ipython().run_line_magic('matplotlib', 'inline')
from matplotlib import pyplot as plt
vertices.append(vertices[0]) #so that we draw a line back to the beginning
plt.plot([val[0] for val in vertices], [val[1] for val in vertices])


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# Object-Oriented approach

class Polygon:
    """A new class named Polygon."""
    
    def __init__(self, vertices):
        self.vertices = vertices
        print("(Creating an instance of the class Polygon)")

    def perimeter(self):
        total = 0
        for i in range(len(self.vertices)):
            vertex1 = self.vertices[i]
            vertex2 = self.vertices[(i+1) % len(self.vertices)]
            distance = math.sqrt((vertex2[0] - vertex1[0]) ** 2
                                 + (vertex2[1] - vertex1[1]) ** 2)
            total += distance
        return total


# In[17]:


a = Polygon([[0, -2], [1, 1], [3, 3], [5, 1], [4, 0], [4, -3]])
a.perimeter()


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