confusion matrix python plot

import matplotlib.pyplot as plt from sklearn.metrics import confusion_matrix, plot_confusion_matrix clf = # define your classifier (Decision Tree, Random Forest etc.) clf.fit(X, y) # fit your classifier # make predictions with your classifier y_pred = clf.predict(X) # optional: get true negative (tn), false positive (fp) # false negative (fn) and true positive (tp) from confusion matrix M = confusion_matrix(y, y_pred) tn, fp, fn, tp = M.ravel() # plotting the confusion matrix plot_confusion_matrix(clf, X, y) plt.show()

By definition, entry i,j in a confusion matrix is the number of observations actually in group i, but predicted to be in group j. Scikit-Learn provides a confusion_matrix function: from sklearn.metrics import confusion_matrix y_actu = [2, 0, 2, 2, 0, 1, 1, 2, 2, 0, 1, 2] y_pred = [0, 0, 2, 1, 0, 2, 1, 0, 2, 0, 2, 2] confusion_matrix(y_actu, y_pred) # Output # array([[3, 0, 0], # [0, 1, 2], # [2, 1, 3]], dtype=int64)

from sklearn.metrics import confusion_matrix cm = confusion_matrix(y_test, y_predicted) cm # after creating the confusion matrix, for better understaning plot the cm. import seaborn as sn plt.figure(figsize = (10,7)) sn.heatmap(cm, annot=True) plt.xlabel('Predicted') plt.ylabel('Truth')

compute confusion matrix using python

import numpy as np

currentDataClass = [1, 3, 3, 2, 5, 5, 3, 2, 1, 4, 3, 2, 1, 1, 2]
predictedClass = [1, 2, 3, 4, 2, 3, 3, 2, 1, 2, 3, 1, 5, 1, 1]

def comp_confmat(actual, predicted):

    classes = np.unique(actual) # extract the different classes
    matrix = np.zeros((len(classes), len(classes))) # initialize the confusion matrix with zeros

    for i in range(len(classes)):
        for j in range(len(classes)):

            matrix[i, j] = np.sum((actual == classes[i]) & (predicted == classes[j]))

    return matrix

comp_confmat(currentDataClass, predictedClass)

array([[3., 0., 0., 0., 1.],
       [2., 1., 0., 1., 0.],
       [0., 1., 3., 0., 0.],
       [0., 1., 0., 0., 0.],
       [0., 1., 1., 0., 0.]])

Posted by: Guest on December-20-2020

Source

Code answers related to "confusion matrix python plot"

Code answers related to "Python"

Browse Popular Code Answers by Language

Answers for "confusion matrix python plot"

Code answers related to "confusion matrix python plot"

Code answers related to "Python"

Python Answers by Framework

Browse Popular Code Answers by Language

Popular Programming Languages

Advertisements

Company

Compilers

Help

Connect with us