31Jul 2018 by Andrew Treadway

How to get live stock prices with Python

Python, Web Scraping
In a previous post, I gave an introduction to the yahoo_fin package. The most updated version of the package includes new functionality allowing you to scrape live stock prices from Yahoo Finance (real-time). In this article, we'll go through a couple ways of getting real-time data from Yahoo Finance for stocks, as well as how to pull cryptocurrency price information. The get_live_price function First, we just need to load the stock_info module from yahoo_fin. Then, obtaining the current price of a stock is as simple as one line of code: Note: Passing tickers is not case-sensitive (upper / lower / mixed doesn't matter). Getting live price with other quote data The live stock price has also been added to the get_quote_table function, which pulls in additional information about the current…
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16Jul 2018 by Andrew Treadway
How to download image files with RoboBrowser

How to download image files with RoboBrowser

Python, Web Scraping
In a previous post, we showed how RoboBrowser can be used to fill out online forms for getting historical weather data from Wunderground. This article will talk about how to use RoboBrowser to batch download collections of image files from Pexels, a site which offers free downloads. If you're looking to work with images, or want to build a training set for an image classifier with Python, this post will help you do that. In the first part of the code, we'll load the RoboBrowser class from the robobrowser package, create a browser object which acts like a web browser, and navigate to the Pexels website. If you actually go to the website, you'll see there's a search box. We can identify this search form using the get_form method. Once…
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23Jun 2018 by Andrew Treadway
ICA on Images with Python

ICA on Images with Python

Machine Learning, Python
Click here to see my recommended reading list. What is Independent Component Analysis (ICA)? If you're already familiar with ICA, feel free to skip below to how we implement it in Python. ICA is a type of dimensionality reduction algorithm that transforms a set of variables to a new set of components; it does so such that that the statistical independence between the new components is maximized. This is similar to Principle Component Analysis (PCA), which maps a collection of variables to statistically uncorrelated components, except that ICA goes a step further by maximizing statistical independence rather than just developing components that are uncorrelated. Like other dimensionality reduction methods, ICA seeks to reduce the number of variables in a set of data, while retaining key information. In the example we…
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25Jan 2018 by Andrew Treadway
Coding with the Yahoo_fin Package

Coding with the Yahoo_fin Package

Python, Web Scraping
Background on yahoo_fin The yahoo_fin package contains functions to scrape stock-related data from Yahoo Finance and NASDAQ. You can view the official documentation by clicking this link, but the below post will provide a few more in-depth examples. Also, please check out my yahoo_fin playlist on YouTube. The first video is below, which covers installation and getting historical / real-time stock prices. The functions in yahoo_fin are divided into two modules, stock_info and options. This post will focus on introducing stock_info. For more on using the options module, check out this post. Let's get started by importing the stock_info module from yahoo_fin. Downloading price data One of the core functions available is called get_data, which retrieves historical price data for an individual stock. To call this function, just pass whatever…
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14Jan 2018 by Andrew Treadway
Timing Python Processes

Timing Python Processes

Python
Timing Python processes is made possible with several different packages. One of the most common ways is using the standard library package, time, which we'll demonstrate with an example. However, another package that is very useful for timing a process -- and particularly telling you how far along a process has come -- is tqdm. As we'll show a little further down the post, tqdm will actually print out a progress bar as a process is running. Basic timing example Suppose we want to scrape the HTML from some collection of links. In this case, we're going to get a collection of URLs from Bloomberg's homepage. To do this, we'll use BeautifulSoup to get a list of full-path URLs. From the code below, this gives us a list of around…
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12Oct 2017 by Andrew Treadway
Word Frequency Analysis

Word Frequency Analysis

Python, Web Scraping
In a previous article, we talked about using Python to scrape stock-related articles from the web. As an extension of this idea, we’re going to show you how to use the NLTK package to figure out how often different words occur in text, using scraped stock articles. Initial Setup Let's import the NLTK package, along with requests and BeautifulSoup, which we'll need to scrape the stock articles. Pulling the data we'll need Below, we're copying code from my scraping stocks article. This gives us a function, scrape_all_articles (along with two other helper functions), which we can use to pull the actual raw text from articles linked to from NASDAQ's website. Let's run our function to pull a few articles on Netflix (ticker symbol 'NFLX'). Above, we use our function to…
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03Oct 2017 by Andrew Treadway
Running Python from the Task Scheduler

Running Python from the Task Scheduler

Python, System Administration
Background Running Python from the Windows Task Scheduler is a really useful capability. It allows you to run Python in production on a Windows system, and can save countless hours of work. For instance, running code like extracting data from a database on an automated, regular basis is a common need at many companies. How to run Python from the command line Before we go into how to schedule a Python script to run, you need to understand how to run Python from the command line. To open the command prompt (command line), press the windows key and type cmd into the search box. Next, suppose your python script is called cool_python_script.py, and is saved under C:\Users. You can run this script from the command prompt by typing the below…
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19Sep 2017 by Andrew Treadway
RoboBrowser: Automating Online Forms

RoboBrowser: Automating Online Forms

Python, Web Scraping
Background RoboBrowser is a Python 3.x package for crawling through the web and submitting online forms. It works similarly to the older Python 2.x package, mechanize. This post is going to give a simple introduction using RoboBrowser to submit a form on Wunderground for scraping historical weather data. Initial setup RoboBrowser can be installed via pip: Let's do the initial setup of the script by loading the RoboBrowser package. We'll also load pandas, as we'll be using that a little bit later. Create RoboBrowser Object Next, we create a RoboBrowser object. This object functions similarly to an actual web browser. It allows you to navigate to different websites, fill in forms, and get HTML from webpages. All of a RoboBrowser object's actions are completely invisible, so you won't actually see…
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16Sep 2017 by Andrew Treadway
Parsing Dates with Pandas

Parsing Dates with Pandas

Pandas, Python
The pandas package is one of the most powerful Python packages available. One useful feature of pandas is its Timestamp method. This provides functionality to convert strings in a variety of formats to dates. The problem we're trying to solve in this article is how to parse dates from strings that may contain additional text / words. We will look at this problem using pandas. In the first step, we'll load the pandas package. Next, let's create a sample string containing a made-up date with other text. For now, assume the dates will not contain spaces (we will re-examine this later). Taking this assumption, we use the split method, available for strings in Python, to create a list of the sub-strings of our variable, string, which are separated by spaces.…
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