Python

It's that time of year again (Decemberween) so I was looking around for a set of addressible LED string lights to set up.

When you get a set of LED lights from your local supermarket they will often be either a single circuit or a set of multiple circuits. This means that they are either all on, or can alternate in a set number of patterns. This is frankly rather dull.

What supermarkets don't have is addressible LED string lights. In these lights each LED on the wire can be address individually to set the colour or brightness. You can tell if the lights are addressible as they will have three cables, two for power, and one for communicating with the lights.

The Tkinter library in Python has a number of file dialogs that allow programs to ask for a file from a user. Using these dialogs it is possible to accept a file from a user and read the contents of that file.

Tkinter comes with a number of different dialogs that have a number of options. These allow users to load directories and files into your python applications, or to point to files that they want to save information into.

In this article we will be concentrating on reading information from files and so the save dialogs will not feature here.

PyScript is a framework that allows browsers to run Python code using HTML and the power of Pyodide and WebAssembly. This means that the Python runtime runs natively and can make full use of any Python code or package available.

PyScript has some amazing features like being able to plug into the browser DOM and bi-directional communication between Python and JavaScript. This essentially means that you can use PyScript as a drop in replacement for JavaScript. It's better than that though as you can also include all of the Python packages you need to do what you want.

As a web developer who has recently been learning more Python, PyScript was very interesting to me. In this article I will look at how to get up and running with PyScript and what tags are available to make the most of the framework.

Inspired by a YouTube video I saw on awesome Numberphile channel about how to draw hitomezashi stitch patterns I decided to recreate them in Python with the aid of the Tkinter Canvas element. The pattern is quite simple and is an example of simple rules creating complex patterns, which I have an interest in.

The idea behind hitomezashi stitch patterns is to take two sets of numbers and draw lines on a grid. One set of numbers is the horizontal and one set is the vertical lines of the grid. The lines drawn are dashed but the key difference is that each start of the line is offset from the start depending on a certain factor. In the video Ayliean MacDonald uses letters of a phrase and offsets the start of the line if the letter is a vowel. She also uses the numbers of pi and offsets if the line if the number is odd.

Conway's game of life, was devised by John Conway in 1970 and is a way of modelling very simple cell population dynamics. The game takes place on a two dimensional board containing a grid of orthogonal cells. The game is technically a zero player game in that the initial setup of the game dictates the eventual evolution of the board.

The rules of the game (taken from wikipedia) are as follows.

1. Any live cell with fewer than two live neighbours dies, as if by underpopulation.
2. Any live cell with two or three live neighbours lives on to the next generation.
3. Any live cell with more than three live neighbours dies, as if by overpopulation.
4. Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction.

For every 'tick' of the game board the rules are evaluated and each cell is kept alive, given life or killed. Through these simple rules a great deal of complexity can be generated.

There are lots of ways to draw objects using the Tkinter Canvas element, but making the canvas elements interactable adds a lot to the applications you create. There are a few things to take into account when binding events like what events to trigger on and how to find out what item triggered what event.

In this article I will address how to set events, how to react to their output and how to find out what element triggered the event.

Let's start by creating a very simple application that contains a Canvas element. In that Canvas we create an oval element that we can use for the rest of the examples.

A calculator is a great application to create when learning how to code as it contains many of the things that most GUI applications will have, including behind the scenes processing of results. Things like triggering events from buttons, accepting user input, and producing output from that input are pretty standard in GUI applications and a calculator has all of them. There are also a couple of features in Python that makes building the application pretty simple. In this article I will look at designing and building the interface using Tkinter, followed by creating the code to process the entered sums into a result.

The Canvas element that comes with Tkinter is quite versatile. Out of the box you can draw simple basic shapes like squares and circles, but also lines and more complex shapes made up of points. You can even add text and images to the canvas.

This article will go through all of the different types of items you can draw using the Tkinter Canvas object.

Before getting into that, it's important to understand how coordinates are used on a canvas object. Drawing items on a canvas requires the use of an x and y coordinate to pinpoint where the item is to be drawn. All points are relative to the top left hand corner, so a coordinate of 0,0 would be right in the top left corner.

I recently saw a design of a physical clock that inspired me to go about creating one using Python and Tkinter. The clock was essentially a wall of letters with lights behind that light up depending on what time it is as a sentence, so it would show the time like "It is 1 o'clock". Without the lights the clock looks like a jumble of letters, it is only when the relevant letters are lit from behind is on that the relevant time is displayed.

The original clock was of a proprietary design so I set about creating one that was based more on an open source clock design that I found. That clock design I found didn't display the AM or PM of the time, so I ended up tweaking that design a little anyway.

Changing time into different formats is quite a common thing to do in programming. I have seen examples that change times into Roman numerals and other formats, but I realised I hadn't seen any code that changed the current time into a sentence. This means converting a numeric time value into a sentence that can be read. For example, the time 9:05 can be read as "it is five past nine", or if the time is 9:00 then it would read "it is nine o'clock". At it turns out, there are only a few rules that govern doing this.