Tonight I’m looking at some sorting algorithms in Python. First up are Bubble Sort and Selection sort, both with 
average and worst case runtime, and 
memory. Finally, I’ll look at an iterative and recursive implementation of Merge Sort.
Simple Directed Graph in Python
This is a work in progress, there’s a lot of complex questions you can ask about graphs, but I though it was neat that you could produce an actual graphy looking thing in so few lines of code. This is a directed graph, and you use the graph object to first create nodes, and then define (unweighted) edges between them or to themselves. The __repr__() method just lists the node data, whatever that is, with an ASCII arrow pointing to another node’s data.
Doubly Linked List in Python
Here is round two for linked lists, the doubly linked list. It’s not very much more complex than a singly linked list. Breaking things into cases using the self.count attribute makes the code easier to read and reason about.
Another Simple Tree in Python
I’ve posted before about creating a tree in Python, but I like this implementation better. It uses a nested class to represent the nodes of the tree, and an interesting construction (line 11) that is a result of that nested class. Also, I do a simple pre-order traversal. I’ll flesh this guy out in later posts.
Singly Linked List in Python
I was reading about data structures this evening and I worked out simple singly linked list. The neat thing about this implementation is that a I made it iterable, also. I’d originally wanted to provide a minimal working singly linked list, and then add features and testing with explanations, but it’s been a long day. This example assumes that you’re using Python2.7; version 3 provides a __next__ class method.
Use Vagrant to Manage an OEL6 Virtual Machine
Vagrant is a tool that you can use to set up, configure, and access a VM through the command line. This is a life changer. I love it. In this post I’ll walk through setting up an OEL6 virtual machine, installing a non-ancient version of Python, and configuring the port forwarding so that you can use it for backend web development. (The port forwarding is not obvious on RHEL/OEL.)
Using simpleldap
Recently, I thought I needed to use simpleldap–it turned out that I instead needed to reconfigure NGINX. At any rate, this was my experience with simpleldap.
Direct and Delegated Event Handlers in jQuery
An alternate title might be: how to bind event handlers to new, or dynamically generated, table rows. When using jQuery, we attach sets of instructions to different parts of an HTML document using selectors. Suppose you wanted to attach some functionality to some text in a table, for example, when you click on a row in a table, it brings up a new table below the first table. This is actually kind of tricky, it turns out that there is a distinction between direct and delegated event handlers.
Using PyWavelets to Remove High Frequency Noise
I ran across an interesting blog post from 2012 that described how to use the PyWavelets module to remove noise from signals. I had been looking for a technique for smoothing signals without smoothing over peaks and sharp shifts, and I had completely forgotten about using wavelets.
Using Sessions in Flask
In this post I’ll provide an example of using session management in Flask. This is useful when you need to recover persistent data across different endpoints in your application. In this example, we set the permanent attribute of the session object to True in order to ensure that the session data lasts indefinitely until it is cleared when the user accesses the root endpoint again. The best practice is to have a timeout on the session data.