Introduction to Python Part II

I. Type of objects in Python:

In Python, every object has its own class – or type of data. The in-depth tutorial can be found on the web, for example, https://jeffknupp.com/blog/2014/06/18/improve-your-python-python-classes-and-object-oriented-programming/. In this tutorial, I will introduce some basic type in Python.

To check type of a variable, data, you can use function type(variable)

+ Numbers: most frequently use is float and int type. The float type uses decimal while the int rounds number. Below is the example of using these type of number. To convert to int and float type, we use int(variable) and float(variable). A number can take numeric operations like +(add), – (subtract), *(multiply), /(divide), % (modulo), ** (exponential)

screen-shot-2016-12-05-at-1-04-06-pm

+ Strings: any character information, that in between ‘ ‘ or ” “.  Strings can be joined together by using + operation.

screen-shot-2016-12-05-at-1-08-31-pm

+ List: Python often uses compound data types, used to group together with other values. The most versatile is the list, which can be written as a list of comma-separated values (items) between square brackets. Lists might contain items of different types: numbers, string or list itself (a list of lists). This type is a basic type to analyze data in Python because it makes you able to access data with ordering.

II. Function and method

In Python,methods are associated with object instances or classes; functions aren’t. When Python dispatches (calls) a method, then it binds the first parameter of that call to the appropriate object reference. A function often has the form of function(argument) while an argument can be any kind of data type (number, string, list). A method must be associated with a type of object and often have the form of object.method(argument) with an object is the suitable type to do a method.

Let’s do some practice and take the list as an example. Screen Shot 2016-12-05 at 1.29.13 PM.png

The functions used in here are len (return the length of an object – how many objects in a list) and print (display an object on screen). The methods used in here are append(add an object to a list) and reverse (reverse the order of objects in a list).

 

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