diff --git a/machine_learning/dbscan.py b/machine_learning/dbscan.py new file mode 100644 index 000000000..f55037896 --- /dev/null +++ b/machine_learning/dbscan.py @@ -0,0 +1,190 @@ +''' + +Author : Gowtham Kamalasekar +LinkedIn : https://www.linkedin.com/in/gowtham-kamalasekar/ + +''' +import math + +import matplotlib.pyplot as plt +import pandas as pd +from typing import dict, list + +class DbScan: + + ''' + DBSCAN Algorithm : + Density-Based Spatial Clustering Of Applications With Noise + Refer this website for more details : https://en.wikipedia.org/wiki/DBSCAN + + Functions: + ---------- + __init__() : Constructor that sets minPts, radius and file + perform_dbscan() : Invoked by constructor and calculates the core + and noise points and returns a dictionary. + print_dbscan() : Prints the core and noise points along + with stating if the noise are border points or not. + plot_dbscan() : Plots the points to show the core and noise point. + + To create a object + ------------------ + import dbscan + obj = dbscan.DbScan(minpts, radius, file) + obj.print_dbscan() + obj.plot_dbscan() + ''' + def __init__(self, minpts : int, radius : int, file : str = + ({'x': 3, 'y': 7}, {'x': 4, 'y': 6}, {'x': 5, 'y': 5}, + {'x': 6, 'y': 4},{'x': 7, 'y': 3}, {'x': 6, 'y': 2}, + {'x': 7, 'y': 2}, {'x': 8, 'y': 4},{'x': 3, 'y': 3}, + {'x': 2, 'y': 6}, {'x': 3, 'y': 5}, {'x': 2, 'y': 4}) + ) -> None: + ''' + Constructor + + Args: + ----------- + minpts (int) : Minimum number of points needed to be + within the radius to considered as core + radius (int) : The radius from a given core point where + other core points can be considered as core + file (csv) : CSV file location. Should contain x and y + coordinate value for each point. + + Example : + minPts = 4 + radius = 1.9 + file = 'data_dbscan.csv' + + File Structure of CSV Data: + --------------------------- + _____ + x | y + ----- + 3 | 7 + 4 | 6 + 5 | 5 + 6 | 4 + 7 | 3 + ----- + ''' + self.minpts = minpts + self.radius = radius + self.file = file + self.dict1 = self.perform_dbscan() + def perform_dbscan(self) -> dict[int, list[int]]: + ''' + Args: + ----------- + None + + Return: + -------- + Dictionary with points and the list + of points that lie in its radius + + >>> result = DbScan(4, 1.9).perform_dbscan() + >>> for key in sorted(result): + ... print(key, sorted(result[key])) + 1 [1, 2, 10] + 2 [1, 2, 3, 11] + 3 [2, 3, 4] + 4 [3, 4, 5] + 5 [4, 5, 6, 7, 8] + 6 [5, 6, 7] + 7 [5, 6, 7] + 8 [5, 8] + 9 [9, 12] + 10 [1, 10, 11] + 11 [2, 10, 11, 12] + 12 [9, 11, 12] + + ''' + if type(self.file) is str: + data = pd.read_csv(self.file) + else: + data = pd.DataFrame(list(self.file)) + e = self.radius + dict1 = {} + for i in range(len(data)): + for j in range(len(data)): + dist = math.sqrt(pow(data['x'][j] - data['x'][i],2) + + pow(data['y'][j] - data['y'][i],2)) + if dist < e: + if i+1 in dict1: + dict1[i+1].append(j+1) + else: + dict1[i+1] = [j+1,] + return dict1 + def print_dbscan(self) -> None: + ''' + Outputs: + -------- + Prints each point and if it is a core or a noise (w/ border) + + >>> DbScan(4,1.9).print_dbscan() + 1 [1, 2, 10] ---> Noise ---> Border + 2 [1, 2, 3, 11] ---> Core + 3 [2, 3, 4] ---> Noise ---> Border + 4 [3, 4, 5] ---> Noise ---> Border + 5 [4, 5, 6, 7, 8] ---> Core + 6 [5, 6, 7] ---> Noise ---> Border + 7 [5, 6, 7] ---> Noise ---> Border + 8 [5, 8] ---> Noise ---> Border + 9 [9, 12] ---> Noise + 10 [1, 10, 11] ---> Noise ---> Border + 11 [2, 10, 11, 12] ---> Core + 12 [9, 11, 12] ---> Noise ---> Border + ''' + for i in self.dict1: + print(i," ",self.dict1[i], end=' ---> ') + if len(self.dict1[i]) >= self.minpts: + print("Core") + else: + for j in self.dict1: + if ( + i != j + and len(self.dict1[j]) >= self.minpts + and i in self.dict1[j] + ): + print("Noise ---> Border") + break + else: + print("Noise") + def plot_dbscan(self) -> None: + ''' + Output: + ------- + A matplotlib plot that show points as core and noise along + with the circle that lie within it. + + >>> DbScan(4,1.9).plot_dbscan() + Plotted Successfully + ''' + if type(self.file) is str: + data = pd.read_csv(self.file) + else: + data = pd.DataFrame(list(self.file)) + e = self.radius + for i in self.dict1: + if len(self.dict1[i]) >= self.minpts: + plt.scatter(data['x'][i-1], data['y'][i-1], color='red') + circle = plt.Circle((data['x'][i-1], data['y'][i-1]), + e, color='blue', fill=False) + plt.gca().add_artist(circle) + plt.text(data['x'][i-1], data['y'][i-1], + 'P'+str(i), ha='center', va='bottom') + else: + plt.scatter(data['x'][i-1], data['y'][i-1], color='green') + plt.text(data['x'][i-1], data['y'][i-1], + 'P'+str(i), ha='center', va='bottom') + plt.xlabel('X') + plt.ylabel('Y') + plt.title('DBSCAN Clustering') + plt.legend(['Core','Noise']) + plt.show() + print("Plotted Successfully") + +if __name__ == "__main__": + import doctest + doctest.testmod()