Tag: programming


A Singleton Configuration Class in Python

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Overview

In this post we cover a strategy for managing configurations for programs using a Singleton pattern to create a static Config class.

This allows the user to create an instance of the Config class, pointing it to a specific config file, which it loads into memory.

The Config class provides several static methods for accessing configuration options from the config file. Here's an example of its usage:

Config('/path/to/config.json')

if Config.get_foo() == "bar":
    do_stuff()

The …



Tags:    python    programming    patterns    design patterns    registry    computer science   


Python: From Args to Kwargs

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Overview

In this short blog post, we talk about how and when you can take a method signature that defines input positional arguments by name, like this:

def foo(arg1, arg2, arg3):
    pass

and write code that will return a dictionary containing a keyword arguments-like structure:

>>> foo('red', 'blue', 'green')
{
    'arg1': 'red',
    'arg2': 'blue',
    'arg3': 'green'
}

We will cover an example of writing a decorator that utilizes input arguments from both the decorator and from the …



Tags:    python    programming    arguments    functions    methods    parameters   


Python Patterns: The Registry

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Overview

This post is a summary of a useful Python programming pattern called the Registry pattern.

The Registry pattern is a way of keeping track of all subclasses of a given class.

More details about this pattern are available at https://github.com/faif/python-patterns.

What is the Registry Pattern …



Tags:    python    programming    patterns    design patterns    registry    computer science   


A Few of My Favorite PEPs

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What's your favorite PEP?

PEPs, or Python Enhancement Proposals, are documents in which features, additions, or general ideas are proposed as additions to the core Python language.

As a Python user, we believe it's important to ask questions like this.

Picking a "favorite PEP" is not just about having a ready and clever answer to a question you might expect in a technical interview; the PEP documents really are important, and really do …



Tags:    python    pep    computer science    programming   


Context Managers in Python

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A Predicament

Recently we spent some time contributing to dib-lab/eelpond (renamed to elvers), an executable Snakemake workflow for running the eelpond mRNAseq workflow.

In the process of tracking down a confusing bug in the Snakemake workflow, we used Snakemake's ability to print a directed acyclic graph (hereafter referred to as a dag) representing its task graph. Snakemake prints the dot …



Tags:    context managers    testing    python    programming   


CSE 143 Final Project: Hilbert Sort: 3. The Code

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This is the third in a series of three posts detailing the Hilbert Sort problem, its solution, and its implementation. This post deals with the code to solve the Hilbert Sort problem.

Hilbert Sort: Pseudocode

From our prior post, here is the psudocode for our Hilbert Sort function:

define hilbert_sort( unsorted queue, square dimension ):
    create southwest queue
    create northwest queue
    create northeast queue
    create southeast queue
    for each point:
        if in southwest:
            create new point using X -> Y, Y -> X
            add to southwest queue
        if in northwest …



CSE 143 Final Project: Hilbert Sort: 2. The Solution Algorithm

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This is the second in a series of three posts detailing the Hilbert Sort problem, its solution, and its implementation. This post solves the problem.

Hilbert Sort Problem

In the prior post, we covered the Hilbert Sort problem, but we state it once more succinctly here before detailing a solution to the problem.

The Hilbert Sort problem asks the following: given a set of labeled \((x,y)\) points, how can we sort the points according to the order …




CSE 143 Final Project: Hilbert Sort: 1. The Problem

Posted in Computer Science

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Table of Contents

This is the first in a series of three posts detailing the Hilbert Sort problem, its solution, and its implementation. This post sets up the problem.

Hilbert Sort: Motivation

In the next few series of posts, we will cover the Hilbert Sort problem, how it works, and how to implement it.
However, before we describe the problem further, let's start with some motivation for solving this problem.

Suppose we're dealing with a very large number of independent objects …




CSE 143 Final Project: Classy

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Problem Description

Comedian John Cleese, in his memoir So Anyway..., described the social classes of his mother and father as "upper-uper-lower-middle class" and "middle-middle-middle-lower-middle class", respectively. Write a program that will sort individuals based on a labeling of their social standing by class.

The three main classes are upper, middle, and lower. Classes progress hierarchically from right to left. For example, lower-upper would come before lower-lower. There is also ordering within a class, so upper-upper is a higher class than middle-upper.

Once you have reached …




CSE 143 Final Project: Checkers

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The Problem

This is a programming challenge that was assigned to some of my CSE 143 students as a final project for their class.

The origin of this problem was the Association of Computing Machinery (ACM)'s International Collegiate Programming Competition (ICPC), in particular the Pacific Northwest Regional Competition, Division 1 challenges from 2015.

Link to Pacific NW ACM ICPC page.

Problem Description: Checkers

In the Checkers problem …