KNN in Practice - Classification

 Problem statement :

Finding whether a patient has Cancer or not ?? and classifying a new patient based on her reports(features)

import numpy as np

import pandas as pd

 importing data :

from sklearn.datasets import load_breast_cancer

data=load_breast_cancer()

data.data

data.feature_names

array([' malignant', 'benign'])

In this we have, two categories: 'Malignant' the one who has cancer and 'Benign' means no cancer.

data.target

data.target_names

 Create a dataframe:

df=pd.DataFrame(np.c_[data.data,data.target],columns=[list(data.feature_names)+['target']])

df.head()

df.shape

(569, 31)

Split the data:

x=df.iloc[:,0:-1]

y=df.iloc[:,-1]

from sklearn.model_selection import train_test_split

x_train,x_test,y_train,y_test=train_test_split(x,y,test_size=0.2,random_state=50)

print('shape of x_train:',x_train.shape)

print('shape of y_train:',y_train.shape)

print('shape of x_test:',x_test.shape)

print('shape of y_test:',y_test.shape)

shape of x_train: (455, 30)
shape of y_train: (455,)
shape of x_test: (114, 30)
shape of y_test: (114,)

Implementing KNN Classifier :

from sklearn.neighbors import KNeighborsClassifier

classifier=KNeighborsClassifier(n_neighbors=5)

classifier.fit(x_train,y_train)

Accuracy:

classifier.score(x_test,y_test)

0.91228070175

Here we have a new patient test reports, by this we need to classify the patient whether she has cancer or not i.e is she belongs to 'Malignant' , or 'Benign'. 

patient1 = [17.99,

 10.38,

 122.8,

 1001.0,

 0.1184,

 0.2776,

 0.3001,

 0.1471,

 0.2419,

 0.07871,

 1.095,

 0.9053,

 8.589,

 153.4,

 0.006399,

 0.04904,

 0.05373,

 0.01587,

 0.03003,

 0.006193,

 25.38,

 17.33,

 184.6,

 2019.0,

 0.1622,

 0.6656,

 0.7119,

 0.2654,

 0.4601,

 0.1189]




patient1=np.array([patient1]) patient1




classifier.predict(patient1)




pred=classifier.predict(patient1) if pred[0]==0: print("patient has cancer (malignant tumor)") else: print("patient has no cancer (malignant benign)")




patient has cancer (malignant tumor)