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, […]

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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 […]

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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 […]

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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 […]

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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 […]

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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 […]

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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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Python Circular Imports

What is a Circular Dependency? A circular dependency occurs when two or more modules depend on each other. This is due to the fact that each module is defined in terms of the other (See Figure 1). For example: functionA(): functionB() And functionB(): functionA() The code above depicts a fairly obvious circular dependency. functionA() calls functionB(), thus depending on it, and functionB() calls functionA(). This type of circular dependency has some obvious problems, which we’ll describe a bit further in […]

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Python Tutorial for Absolute Beginners

Python is one of the most widely used languages out there. Be it web development, machine learning and AI, or even micro-controller programming, Python has found its place just about everywhere. This article provides a brief introduction to Python for beginners to the language. The article is aimed at absolute beginners with no previous Python experience, although some previous programming knowledge will help, but is not necessarily required. I’ve found that the best way to learn is to try to […]

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Append vs Extend in Python Lists

Adding Elements to a List Lists are one of the most useful data structures available in Python, or really any programming language, since they’re used in so many different algorithms and solutions. Once we have created a list, often times we may need to add new elements to it, whether it be at the end, beginning, or somewhere in between. Python offers us three different methods to do so. In this article I’ll be showing the differences between the append, […]

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