/IntroToWebScraping

Learn to Code: Introduction Web Scraping

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About me:

Hello I'm Chris Huie. I'm the Phoenix Tech Evangelist here at Galvanize!

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What this workshop is

A super friendly introduction to web scraping No previous experience expected, but some concepts may be confusing if you have never programmed before. If you get too lost let me know!

You can't learn EVERYTHING in ~2 hours. But you can learn enough to get excited and comfortable to keep working and learning on your own!

  • This course is for absolute beginners
  • Ask Questions!
  • Answer Questions!
  • Help others when you can
  • Its ok to get stuck, just ask for help!
  • Feel free to move ahead
  • Be patient and nice

Overview

The goal of this brief course is to provide you with a fun introduction to web Scraping Python.

Here's what we'll be doing:

  • A primer on some technologies we're going to use
  • Building a simple web scraper with Python
  • I'll leave you with a coupl challenges at the end. You can try to complete them here if we have time, or try them at home

Web Scraping

What is it?

I usually describe it as using a program to get data from the web by pulling content without an API(Application Program Interface).

Many sites have APIs you can connect to and use to pull data from. Such as the Twitter API. This is great! But sometimes you need data from a site that doesn't have an API. Thats what we're going to look at in this workshop. A lot of weather data can usually be pulled from an API.

Where is it used?

Really any where you think it would be appriate to gather data.

Some people I've met have built web scraper to look for jobs & find apartments.

Companies may search for email or contact information

Competitive analysis on a competing company, what prices do they have?

Realtors may scrape housing listings

Understand sentiment and words in reviews

Anytime you want data!

Before we build

HTML Basics

HTML is one of the main building blocks of the web!

Some common Tags(Elements):

  • <html> designates an HTML document

  • <head> contains undisplayed information about the document

  • <title> Creates a title for the document

  • <body> contains displayed information

  • <header>, <main>, <footer> denotes which part of the page elements belong

  • <h1> - <h6> create section headings (h1 biggest, h6 Smallest)

  • <p> creates paragraphs

  • <a href=""></a> (anchor), activates a link in the page

  • <ul>, <ol> creates lists

    • <li> contains items in lists

  • <br> Inserts a single line break

Self-closing Tags:

most HTML tags require an opening and a closing tag. There are a few however that do not:

  • <img src=""> creates an image in the page
  • <br> creates a break in the content
  • <input type=""> creates an input field
  • <hr> Creates a line in the page
IDs, Classes

IDs and classes are very similar. These are used to target specific elements(You'll see more examples in CSS section).

  • <h1 id="profile-header"></h1>

  • <h1 class="subject-header"></h1>

  • IDs should only be used once on a page. IDs can also be used to bring the user to a specific part of the page. your-site/#profile-picture will load the page near the profile picture.

  • Classes can be used multiple times on a page.

See More tags here

Learn more HTML here

Inspect element of a web page

  • Go to a web page
  • right click
  • select inspect element
  • you should not see a pop up or frame showing the HTML of a web page.

Python

We're going to be using python to do our web scraping.

Don't worry if you've never programmed in python or at all before, I will explain concepts along the way. And if you want me to repeat something just ask! We'll be doing a free intro to python workshop in January too if you want to go deeper! Or go through our free data science prep material.

Requests

We will use the Requests module to visit a URL and get web elements.

Beautiful Soup

We will use Beautiful Soup is used to parse HTML and extract the information we need.

Pandas

We'll use pandas to do some analysis and visulizations on our data

NLTK

We'll use NLTK(Natural Language Toolkit) to do some simple natural language processing on some text.

Google Colab

We'll use google collab as our editor. It comes preinstalled with everything we need.

Lets scrape data from the web!

Here's what we will do!

  • Look at data tags
  • write code to get data
  • Look at scraped data
  • get specific parts of the data
  • transform the data for different use case
  • minor visulizations for the data so we can understand it better
  • Basic Sentiment Analysis on headlines to see how negative they are

Get Started:

  • Open the notebook for this workshop here.

Make a copy by clicking file and make copy or save to drive

Awesome, you now know the basics of web scraping!

Book mark this repo or the colla notebook and experiement with the code. Try a different website.