如何使用Python Scikit-learn实现线性分类？

# Import required librariesimport sklearnimport numpy as npimport matplotlib.pyplot as plt# %matplotlib inline# Loading Iris flower datasetfrom sklearn import datasetsiris = datasets.load_iris()X_data, y_data = iris.data, iris.target# Print iris data shapeprint ("Original Dataset Shape:",X_data.shape, y_data.shape)# Dividing dataset into training and testing dataset and standarized the featuresfrom sklearn.model_selection import train_test_splitfrom sklearn.preprocessing import StandardScaler# Getting the Iris dataset with only the first two attributesX, y = X_data[:,:2], y_data# Split the dataset into a training and a testing set(20 percent)X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.20, random_state=1)print ("Testing Dataset Shape:", X_train.shape, y_train.shape)# Standarize the featuresscaler = StandardScaler().fit(X_train)X_train = scaler.transform(X_train)X_test = scaler.transform(X_test)# Plot the dataset# Set the figure sizeplt.figure(figsize=(7.16, 3.50))plt.subplots_adjust(bottom=0.05, top=0.9, left=0.05, right=0.95)plt.title('Training instances', size ='18')colors = ['orange', 'green', 'cyan']for i in range(len(colors)):   px = X_train[:, 0][y_train == i]   py = X_train[:, 1][y_train == i]   plt.scatter(px, py, c=colors[i])   plt.legend(iris.target_names)plt.xlabel('Sepal length')plt.ylabel('Sepal width')plt.show()# create the linear model SGDclassifierfrom sklearn.linear_model import SGDClassifierlinear_clf = SGDClassifier()# Train the classifier using fit() functionlinear_clf.fit(X_train, y_train)# Print the learned coeficientsprint ("The coefficients of the linear boundary are:", linear_clf.coef_)print ("The point of intersection of the line are:",linear_clf.intercept_)# Evaluate the resultfrom sklearn import metricsy_train_pred = linear_clf.predict(X_train)print ("The Accuracy of our classifier is:", metrics.accuracy_score(y_train, y_train_pred)*100)

Original Dataset Shape: (150, 4) (150,)Testing Dataset Shape: (120, 2) (120,)The coefficients of the linear boundary are: [[-28.85486061 13.42772422][ 2.54806641 -5.04803702][ 7.03088805 -0.73391906]]The point of intersection of the line are: [-19.61738307 -3.54055412 -0.35387805]