Home arrow Python arrow Page 2 - Python: Count on It

Decimals, Division, and Floats - Python

We touched on how numbers work in Python a while back in the beginning of our series on Python. In the past few tutorials we discussed strings and how to manipulate them and some of the string methods. Here, in this article, we will go over some of the math modules and discuss different uses for numbers in Python.

  1. Python: Count on It
  2. Decimals, Division, and Floats
  3. Floating Points
  4. Built-in Math Functions
By: James Payne
Rating: starstarstarstarstar / 3
February 19, 2008

print this article



Python converts your integer into a long if need be automatically, so you don't really need to concern yourself with this issue. However, there is an issue you should be concerned about, and that is in regards to division. Try typing the following in the command prompt of your Python Shell:

>>> 14/6

As you can see, your result is 2. However, if you multiply 6 * 2, you will get 12. So clearly the division isn't right. Unless you are in third grade, or are a complete moron, you know that this is because there was a remainder, and the number has been rounded down. This occurs when you divide two integers. If you want to get the true value, there are several methods you can use, each of which is shown below:

>>> 14/6.0


The above example is probably the simplest. All you do is change one of the numbers into a decimal and it will give you the full result. Don't worry about the long line of numbers following the decimal; we'll learn to shorten that later.

Another way to fix the problem is with the decimal module, like so:

>>> from decimal import Decimal

>>> Decimal(14)/Decimal(6)


The decimal module is a built-in module that gives more accurate results than your typical binary floating point math, particularly when you use it for certain types of calculations, such as calculating percentages, equality testing, and my buddy the modulo calculation.

The line above, from decimal import Decimal, is how we call the decimal module.

One final method to fix this problem is using the mighty Guido Van Rossum's __future__ module. Please note, (I have yet to see anyone explain this, and save a writer a day of banging his head on the desk) that the __future__ module is comprised of two _ on each side, not one, as in _future_. Here is how the __future__ module works. Can I say that one more time? You bet I can...__future__ module:

>>> from __future__ import division

>>> 13/3


Be careful not to use the __future__ module too often however; rumor has it that Van Rossum turns into a giant Sasquatch (as opposed to the midget kind) every time it is invoked.

>>> More Python Articles          >>> More By James Payne

blog comments powered by Disqus
escort Bursa Bursa escort Antalya eskort


- Python Big Data Company Gets DARPA Funding
- Python 32 Now Available
- Final Alpha for Python 3.2 is Released
- Python 3.1: String Formatting
- Python 3.1: Strings and Quotes
- Python 3.1: Programming Basics and Strings
- Tuples and Other Python Object Types
- The Dictionary Python Object Type
- String and List Python Object Types
- Introducing Python Object Types
- Mobile Programming using PyS60: Advanced UI ...
- Nested Functions in Python
- Python Parameters, Functions and Arguments
- Python Statements and Functions
- Statements and Iterators in Python

Developer Shed Affiliates


Dev Shed Tutorial Topics: