KNN

Features of dataset:

• sepal_length - sepal length in cm
• sepal_width - sepal width in cm 
• petal_length - petal length in cm
• petal_width - petal width in cm
• 
  
• Class:
  1 - Iris Setosa
  2 - Iris Versicolour
  3 - Iris Virginica
• Given the features of a flower we need to predict its class.  
  

  Import required libraries

  
  # For handling datasets
  import pandas as pd
  
  # For plotting graphs
  from matplotlib import pyplot as plt
  
  # Import the sklearn library for KNN
  from sklearn.neighbors import KNeighborsClassifier
  

  Import dataset

  
  # Import the csv file
  df = pd.read_csv('data.csv')
  
  print df.head()
  '''
  Output:
     sepal_length  sepal_width  petal_length   
  0           5.1          3.5           1.4
  1           4.9          3.0           1.4 
  2           4.7          3.2           1.3  
  3           4.6          3.1           1.5 
  4           5.0          3.6           1.4 
  
  petal_width  class
          0.2      1
          0.2      1
          0.2      1
          0.2      1
          0.2      1   
  '''
  
  
  

  Prepare data for training

  
  # Prepare the training set
  X = df.loc[:,'sepal_length':'petal_width']
  Y = df.loc[:,'class']
  

  Train the model

  
  knn = KNeighborsClassifier()
  
  # Train the model
  knn.fit(X,Y)
  

  Test the model

  
  # Prepare the test data
  X_test = [[4.9,7.0,1.2,0.2],
           [6.0,2.9,4.5,1.5],
           [6.1,2.6,5.6,1.2]]
  
  # Test the model(returns the class)
  prediction = knn.predict(X_test)
  
  print prediction
  '''
  Output:
  [1 2 3] 
  '''
  

  Plotting

  
  # Plot the relation of each 
  # feature with each class
  plt.xlabel('Feature')
  plt.ylabel('Class') 
  
  X = df.loc[:,'sepal_length']
  Y = df.loc[:,'class']
  plt.scatter(X, Y,color='blue'
          ,label='sepal_length')
  
  X = df.loc[:,'sepal_width']
  Y = df.loc[:,'class']
  plt.scatter(X, Y,color='green'
          ,label='sepal_width')
  
  X = df.loc[:,'petal_length']
  Y = df.loc[:,'class']
  plt.scatter(X, Y,color='red'
          ,label='petal_length')
  
  X = df.loc[:,'petal_width']
  Y = df.loc[:,'class']
  plt.scatter(X, Y,color='black'
          ,label='petal_width')
  
  plt.legend(loc=4, prop={'size': 5})
  plt.show()