Building a Polar Point From Cartesian Coordinates

00:00 Building a Polar Point From Cartesian Coordinates. For a more elaborate example of providing multiple constructors using class methods, let’s say you have a class representing a polar point in a math-related application.

00:15 You need a way to make your class more flexible so that you can construct new instances using Cartesian coordinates as well. On-screen, you can see how to write a constructor to meet this requirement.

00:50 .from_cartesian() takes two arguments representing a given point’s x and y Cartesian coordinates. Then the method calculates the required distance and angle to construct the corresponding PolarPoint object.

01:08 Finally, .from_cartesian() returns a new instance of the class.

01:36 On-screen, you can see the class working using both coordinate systems. First you create a point using polar coordinates, and then one using Cartesian coordinates.

01:55 In these examples, you use the standard instantiation process and your alternative constructor, .from_cartesian(), to create PolarPoint instances using conceptually different initialization arguments.

02:10 In the next section of the course, you’ll take a closer look at the use of multiple constructors in Python’s built-in and standard-library classes.