Contour plot

The contour plot is typically used to display how the error varies with varying coefficients that are being optimized in a machine learning algorithm, such as linear regression. If the linear regression coefficients are theta0 and theta1, and the error between the predicted value and the actual value is a Loss, then for a given Loss value, all the values of theta0 and theta1 form a contour. For different values of Loss, different contours are formed by varying the values of theta0 and theta1.