Python tutorials

September 21, 2020 Python Leave a comment

Reading and Writing CSV Files in Python

What is a CSV File? A CSV (Comma Separated Values) file is a file that uses a certain formatting for storing data. This file format organizes information, containing one record per line, with each field (column) separated by a delimiter. The delimiter most commonly used is usually a comma. This format is so common that it has actually been standardized in the RFC 4180. However, this standard isn’t always followed and there is a lack of universal standard usage. The […]

September 21, 2020 Python Leave a comment

Command Line Arguments in Python

Overview With Python being such a popular programming language, as well as having support for most operating systems, it’s become widely used to create command line tools for many purposes. These tools can range from simple CLI apps to those that are more complex, like AWS’ awscli tool. Complex tools like this are typically controlled by the user via command line arguments, which allows the user to use specific commands, set options, and more. For example, these options could tell […]

September 21, 2020 Python Leave a comment

Read a File Line-by-Line in Python

Introduction Over the course of my working life I have had the opportunity to use many programming concepts and technologies to do countless things. Some of these things involve relatively low-value fruits of my labor, such as automating the error prone or mundane like report generation, task automation, and general data reformatting. Others have been much more valuable, such as developing data products, web applications, and data analysis and processing pipelines. One thing that is notable about nearly all of […]

September 21, 2020 Python Leave a comment

Parallel Processing in Python

Introduction When you start a program on your machine it runs in its own “bubble” which is completely separate from other programs that are active at the same time. This “bubble” is called a process, and comprises everything which is needed to manage this program call. For example, this so-called process environment includes the memory pages the process has in use, the file handles this process has opened, both user and group access rights, and its entire command line call, […]

September 21, 2020 Python Leave a comment

Serving Static Files with Flask

Setting Up Flask Flask is a great choice for building web applications in a modular way using Python. Unlike Django and other analogues like Ruby on Rails, Flask is a micro-framework. This means it includes only what is necessary to do core web development, leaving the bulk of choices beyond that minimal subset to you. This approach has a huge advantage in keeping your code and workflow simple, particularly on smaller projects. Here we will show you how to serve […]

September 21, 2020 Python Leave a comment

Recursive Model Relationships in Django

The Need for Recursive Relationships There arises many times in the development of modern web applications where the business requirements inherently describe relationships that are recursive. One well known example of such a business rule is in the description of employees and their relationship to their managers, which are also employees. Notice the circular nature of that statement. This is exactly what is meant by a recursive relationship. In this article we will be developing a bare bones demo in […]

September 21, 2020 Python Leave a comment

scikit-learn: Save and Restore Models

On many occasions, while working with the scikit-learn library, you’ll need to save your prediction models to file, and then restore them in order to reuse your previous work to: test your model on new data, compare multiple models, or anything else. This saving procedure is also known as object serialization – representing an object with a stream of bytes, in order to store it on disk, send it over a network or save to a database, while the restoring […]

September 21, 2020 Python Leave a comment

Python Generators

What is a Generator? A Python generator is a function that produces a sequence of results. It works by maintaining its local state, so that the function can resume again exactly where it left off when called subsequent times. Thus, you can think of a generator as something like a powerful iterator. The state of the function is maintained through the use of the keyword yield, which has the following syntax: yield [expression_list] This Python keyword works much like using […]

September 21, 2020 Python Leave a comment

Python: List Files in a Directory

I prefer to work with Python because it is a very flexible programming language, and allows me to interact with the operating system easily. This also includes file system functions. To simply list files in a directory the modules os, subprocess, fnmatch, and pathlib come into play. The following solutions demonstrate how to use these methods effectively. Using os.walk() The os module contains a long list of methods that deal with the filesystem, and the operating system. One of them […]

September 21, 2020 Python Leave a comment

TensorFlow: Save and Restore Models

Training a deep neural network model could take quite some time, depending on the complexity of your model, the amount of data you have, the hardware you’re running your models on, etc. On most of the occasions you’ll need to save your progress to a file, so in case of interruption (or a bug), you’ll be able to continue where you left off. Even more, after a successful training you’ll surely need to re-use the model’s learned parameters to make […]

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