Unpacking a List

Word Frequency Counter

This program makes a count of the words on a webpage. The basic outline of the program is as follows:

(1) Use Beautiful Soup to  crawl a webpage.
(2) Put words from webpage into list.
(3) Pass this word list into a method that cleans up word list.
(4) Pass this clean word list into method that creates a dictionary with key of word and value of number of times word occurs.

See program below:

Creating a Dictionary

Threading

More about Classes and Objects

Errors: Syntax and Exceptions

A syntax error is a problem with the code. An exception error is a problem with the input.

Making a Web Crawler

Downloading CSV File From Web

An outline of the steps to download file from the web:
(1) Import necessary library
(2) Create function that passes url of csv file.
(3) Open url
(4) Read url
(5) Convert what is read to a string
(6) Create CSV file.
(7) Open csv file to write.
(8) write read url to csv file
(9) Close opened csv file

Reading Files

Writing Files

Downloading Image from the Web

Flexible number of arguments

Variable Scope, Another Example

Here is another example of a local variable inside a function that can not be used outside the function.The value area has to be passed to a variable outside the function. I have used a '#' to make the code that does that into a comment and thus we the error that area is not defined.

Variable Scope

In the example below the variable, a , is created outside both functions and can be used by both functions.

 

In the example below the variable a is created inside a function and only that function can use the variable.

 

Setting Default Values

Value is defaulted to unknown.

Return Statement

The return statement is used to return a value to the caller of the function. It returns a value that can be used outside the function. See example below.

Here is a similar program where the area value is not returned. Thus I have embedded the print statement within the function get a similar output.

Continue Statement

Notice the numbers that are not printed.

Generating Random Number and Break Statement

For Loop

PyCharm Installation and test

== Vs is Statement Comparison

Is there a difference between == and is?

is compares if items being compared are from the same object.
== compares if variables are equal.

Updated to Python 3

Module Information

See below to get addition information and/or help about a Python Module.

Frontend, Backend, where does Python fit?

In simple terms front-end is what you see; backend is how it works.

Front-end

The website is usually a mixture of HTML, CSS and Javascript, which are all controlled by the browser.

Back-end

The backend operation is the web application communicating with the server to make changes and store on a server. Languages like PHP, Ruby, and Python are used in this communication.

Built-In Python Modules

Math is an example of a built-in Python module.  If the math module is not imported first the math functions in Python will not work. See example below.

Creating and Importing Modules

A module can be used to save variables and methods. Modules can then be imported into a method. See example below.

Constructors

A constructor is a function that initializes immediately as soon as the objects is created. See example below.

Printing Strings

Update to Market Evaluation Program

An update to the Stock Market Evaluation Program that utilizes Classes and Objects to give some additional information in the form of Strings based on user inputs.

Classes and Self

Self is used as temporary placeholder for the object. See two examples below.

Object Oriented Programming

An object contains built in attributes. These attributes can be data and/or methods. Functions associated with an object are referred to as methods. 

Before an object can be created, a class must be created. A class is a blueprint for an object.
Many objects can refer to the same class.

See below for two examples of creating a class, and then creating an object. 

Tuples as Parameters

Creating Functions

A simple function that returns a sentence with the square of the inputted number.

While Loop

AND Statement

Utilize the AND statement to test two conditions:

Comparison Operators

Simple Python Program to Evaluate Stock Market

Program utilizes print statement, variables, basic math, and comparison operators.

Nesting

An Else/If statement inside another Else/If statement:

Else/ If statement

Using Strings as Variables

Use %S to designate part of string for use as a variable. See example below.

Sorting Method