Last active
April 16, 2018 11:00
-
-
Save oem/ddff9542fc09b3df110f8ac02441a828 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| require 'minitest/autorun' | |
| require 'matrix' | |
| module LinearRegression | |
| def predict(features, theta) | |
| features * theta | |
| end | |
| def cost_function(features, labels, theta) | |
| m = features.row_count | |
| predictions = predict(features, theta) | |
| squared_errors = (predictions - labels).map { |error| error**2 } | |
| (1.0 / (2.0 * m)) * squared_errors.reduce { |a, b| a + b } | |
| end | |
| def normal_equation(features, labels) | |
| (features.transpose * features).inverse * features.transpose * labels | |
| end | |
| end | |
| class TestLinearRegression < MiniTest::Test | |
| include LinearRegression | |
| def setup | |
| @features = Matrix[[10, 1000, 10], [5, 800, 2], [12, 2500, 3]] | |
| @labels = Vector[900, 600, 1800] | |
| @initial_theta = Vector[200, -0.1, -10] | |
| end | |
| def test_predict_with_inital_theta | |
| assert_equal Vector[1800, 900, 2120], predict(@features, @initial_theta) | |
| end | |
| def test_cost_with_initial_theta | |
| assert_equal 167_066.67, cost_function(@features, @labels, @initial_theta).round(2) | |
| end | |
| def test_normal_equation | |
| assert_equal Vector[5.0, 0.675, 17.5], normal_equation(@features, @labels) | |
| end | |
| def test_cost_function_with_optimal_theta | |
| optimal_theta = Vector[5.0, 0.675, 17.5] | |
| assert_equal 0, cost_function(@features, @labels, optimal_theta) | |
| end | |
| def test_predict_with_optimal_theta | |
| optimal_theta = normal_equation(@features, @labels) | |
| assert_equal Vector[900, 600, 1800], predict(@features, optimal_theta) | |
| end | |
| end |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment