`bmi` Module

Introduction

In this assignment you’ll practice

writing functions and modules,
manipulating strings,
converting values to different data types,
doing arithmetic calculations, and
testing modules with doctest.

Problem Description

You want to live a healthy life and use your computer to help you analyze your fitness and health.

Solution Description

Create a module that provides convenience functions for converting imperial measures to metric equivalents, a function to calculate BMI, and two functions that tell you whether you are overweight or underweight according to government BMI standards. Your module will be named bmi and contain the functions listed below.

The BMI formula is:

$$ bmi = \frac{w}{h^2} $$

where

w is weight in kilograms, and
h is height in meters.

`doctest`

The specification for each function is given as a docstring – which you should include in your code – and the types of arguments and return values are given using type hints documented in PEP 484 – Type Hints.

Because each function will have a docstring that includes usage examples formatted as Python interactive sessions, you can use doctest to test your code using this command line invocation:

python -m doctest -v bmi.py

If all the tests pass, then you’ll probably (but not defnitely) get a 100 on this homework.

Required Functions

Implement the following functions in your bmi.py file. For convenience you can simply copy the code below.

IMPORTANT: Do not modify the provided docstrings!

from typing import *

def in2m(inches: float) -> float:
    """Convert inches to meters according to convsersion rule 1m == 39.3701in

    Usage examples:
    >>> abs(in2m(39.3701) - 1) < .01
    True
    """

def lb2kg(pounds: float) -> float:
    """Convert pounds to kilograms according to convsersion rule 1kg == 2.2lb

    Usage examples:
    >>> abs(lb2kg(2.2) - 1) < .01
    True
    """

def bmi(weight: float, height: float) -> float:
    """Return body mass index (BMI) for given weight in kg and height in meters.  
    The BMI formula is bmi = (weight in kg) / (height in meters)^2

    Usage examples:
    >>> abs(bmi(66, 1.72) - 22.309) < .01
    True
    """

def is_overwieght(weight: float, height: float) -> bool:
    """Answer whether the given weight in kg and height in meters is considered
    overweight by government standards (BMI > 25).

    Usage examples:
    >>> is_overwieght(74, 1.72)
    True
    >>> is_overwieght(73, 1.72)
    False
    """

def is_underweight(weight: float, height: float) -> bool:
    """Answer whether the given weight in kg and height in meters is considered
    underweight by government standards (BMI < 18.5).

    Usage examples:
    >>> is_underweight(54, 1.72)
    True
    >>> is_underweight(55, 1.72)
    False
    """

Testing Your Module Interactively

In addition to running the doctests as described above, you can import your bmi module in the Python REPL to test your functions as you write and modify them. For example, ssuming you’re in the same directory as your bmi.py file:

Python 3.5.2 |Continuum Analytics, Inc.| (default, Jul  2 2016, 17:53:06)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import bmi
>>> bmi.bmi(bmi.lb2kg(114), bmi.in2m(65))
19.010279100284023

After you modify your module you’ll need to restart your Python REPL, or reload it using the importlib module:

>>> import importlib as imp
>>> imp.reload(bmi)

bmi Module