Topics by vegaseat

This Python code shows a way to retrieve a picture from a web page and save it to a file.

Some computer languages have a goto statement to break out of deeply nested loops. Python has chosen not to implement the much abused goto. There are other, really more elegant, ways to accomplish the same outcome. Here are three examples.

Yet Another Calculator using wxPython, smaller, but more advanced than the previous one. Wrote this one to test the Curry class, but it didn't work well. So there is no curry there. I found out that one has to be careful with the eval() function. If you write 012 instead …

Let mathematics do your art work! It is amazing how a simple mathematical formula can draw very intricate shapes. Here we draw a fractal tree on a Python Image Library (PIL) blank image, and save the finished drawing as an image file in one of the popular formats. Look at …

The wx.BitmapButton shows an image, great for those folks who think that a picture is worth a thousand words. The snippet gives an example how to load the image, size the button, and put the image on the the button.

Just a small Python program to calculate monthly payments and other costs. I have compared it with some of the calculators available from many of the online mortgage companies, and results seem to match.

In this snippet we are playing around with wxPython's buttons, showing you how to bind the mouse click event, enable and disable, show and hide the buttons. Each button also has a tool-tip (hint) associated with itself.

If you want a variable in a C function to retain its last assigned value, you simply declare it as static. Python does not have static variables, but you can impersonate one in different ways. The default list argument is my preferred option. Here are some examples.

Py2Exe takes your Python code file and packages it into an executable file that you can distribute to a client that does not have Python installed. The executable file contains your byte code, all the required modules and the Python interpreter. It is not a small file. The snippet is …

This small snippet shows how to load and display HTML (Hyper Text Markup Language) with wxPython's HtmlWindow(). This could be particularly useful with instruction and help text. HTML allows you to include pictures, fancy fonts and links.

When I first met folks in Las Vegas that used biorhythm values of the top players in a team to place their bet, I thought they were a little odd. Some of them were successful, but I am sure biorhythms were not the only thing they considered. You can read …

Just in time, a short Python code snippet to calculate the date of Easter Sunday of a given year. This can be expanded to calculate the important date of Mardi Gras too.

Using an SDL (Simple DirectMedia Layer) wrapper is one way to play sound and music with Ruby. I have tested this snippet with .MID .MOD and .WAV files and it performs well. There are several SDL wrappers for Ruby available, I picked RUDL because of its simplicity. RUDL is great …

I took the data of an old State Trivia game and applied it to Python. The data forms a series of lists with matching indexes. One example of how to ask a trivia question, present four possible answers, and how to evaluate the correct answer is given. You can expand …

A list comprehension derives a new list from an existing list, and was adopted by Python from the Haskell language. This snippet tries to explain the development of list comprehension and shows a number of uses, including nested list comprehension. The benefits are simplicity (after an initial learning bump) and …

The lowly soundcard in your PC has fascinating capabilities. All you need is a module that can handle the Musical Instrument Digital Interface (MIDI). Tell the soundcard which instrument to play, specify the musical note, the duration, the beat and other things. The sound chip makes 127 instruments available and …

Boo is new, well at least relatively new. If you are familiar with Python and C#, you can feel right at home. Most of Boo is written in C# by a Python devotee. Boo has static typing, but also mimics dynamic typing by inference. This way you are not in …

The wx.ComboBox is a combination of an editbox and a (dropdown) listbox. It let's the user slect an item from the listbox and puts it in the editbox. In this snippet we use two comboboxes, each used to select an area unit of measurement. Once selected, an area value can …

Not much excitement in that standard wxPython empty window icon. It's time you put a more picturesque icon up there. This snippet shows you how to use an embedded icon or your own icon you have as an icon file in your working folder. Actually, the embedded icon is written …

In this experiment we call the paint event and establish a device context to draw a rectangle and fill it with the color set by the brush. Actually, we will draw 99 random sized and random colored rectangles with a small time delay. Don't worry, it will be faster than …

The wxPython widget wx.Gauge is commonly called a progress bar. In this code snippet I have bound the wx.Gauge to a wx.Slider, as you move the slider so do the indicating bars of the gauge. A second method is explored too, here the gauge indicates the progress of a timed …

Using a wxPython GUI program to find the position of the mouse when clicked within the frame/window. Also sets the color of the frame and changes the cursor to a pencil. The title bar of the frame displays the coordinates of the mouse position.

Create a dictionary with char:count pairs, change the dictionary to a list of (char, count) tuples, sort the list by character and display the result. That's all there is to counting and displaying the characters in a given string. Just a few lines of Python code.

This short code lets you create a base64 encoded image string, that you can copy and paste into your Python program code to display relatively small embedded images. For a typical application see: [url]http://www.daniweb.com/code/snippet393.html[/url]

Small image files can be embedded in Python code using the base64 encoded string of the image. If you have to present a number of small fixed images in your program, embedding might be easier than including a set of image files. Attached files can be lost, and than your …

Here is a generator function using find() to do a search for all the occurances of a substring in a text. It will give you all the positions/indexes within the text where the substring is located. The sample text here can be replaced by text read in from a file.

This snippet takes a look at Python file handling. Different ways to write and read text files, zipped files and memory streams. Investigates how to access only part of a file. Also explores the "read" of a binary image file and performs a hex-dump of the data.

This code shows you how to build a multiline story string that should display similarly to way it shows in the code. It should be relatively easy to maintain.

For loops in Python are quite versatile. The little keyword "in" allows you to loop through the elements of all kinds of sequences, may the elements be numbers, characters, strings, objects like tuples and more. Here is an example comparing range(), xrange() and a generator similar to xrange().

Years ago I wrote a little screen-saver in Delphi that randomly put colorful circles all over the screen. A hit with the secretaries in the office. I modified a simple Tkinter based snippet to put the same colorful circles all over a window form at random locations, random radii and …

VPython's fame is with 3D animated modeling, but it's plotting abilities, while not flashy, are easy to understand and very useful. This program uses VPython to plot math functions y = sin(x) and y = cos(x) and y = sin(x)*cos(x).

This question came up on the forum. How do you swap two numbers without using a temporary variable? I used all the power of my brain to solve this at four o'clock in the morning. In all fairness, swapping two numbers using a temporay variable is about five times faster. …

Python has a module specifically made for timing built-in or owner coded functions. This code snippet explains how to use this feature.

The psyco module has been around for a while and has been used to speed up the Python interpreter. For those of you who think speed is all important, take a look at a typical example. Psyco is similar to Java's just in time compiler. How does psyco do it? …

Python24 introduces the function decorator that lends itself nicely to the timing of a function. As a sample function we are using the ever popular and rather stodgy prime number generator. The prime number generator seems to exist only to fluster students and to make niggling comparisons of the speed …

The Python module zlib allows you to compress a typical text string to about one half its original size. A handy feature when you have to transmit or save a large amount of text or data. It saves you time both writing and later reading back the compressed file. The …

Python uses C syntax to perform bitwise operations. Take a look at code that introduces you to bitwise operations at the binary level.

If you have a Windows computer you can play musical beeps through the internal speaker. In this case it will sound like a very tiny Big Ben, brought to you by the module winsound and its method Beep().

Did you ever want to know how how many square inches are in a square meter? This short Python code allows you to get the answer. It uses a dictionary to simplify the conversions. Could be the start of a nice GUI program using radio buttons.

The Python list container can be used for many practical things. In this somewhat light-hearted introspection of modern day politics we are looking at two lists and attempt to clear out elements that shouldn't be in both lists. No offense to anyone is intended, the outcome with the sets was …

A while ago I created a code snippet in C for the same question. Solving this question with Python is a lot simpler, and on top of that Python takes care of impossible dates with the appropriate error message.

A simple experiment with the ever so popular Mandelbrot fractal graphics, call it mathematical art, nice to look at. This set of experiments loops through a number of colors to make the whole thing more exciting.

Jumping through a few extra hoops allows you to display the common image format jpeg on a panel of the wxPython GUI window. All you need to do is to read in the image file as a binary, convert to a byte stream image and then to a bitmap. Now …

The other day I was looking at my family tree. There are my parents Antonio and Lucy Vegaseat, then my grandparents Alfonso and Ludmilla Vegaseat on my father's side and Roland and Helga Gruenspan on my mother's side. Then come my great grandparents, by now there are eight of those. …

While the calculation of the total resistance of two resistors in parallel is simple, this code shows you how to trap a number of potential errors that come with the entry of the required data. All is wrapped easily into a colorful GUI program, due to the simplicity of the …

The wxNotebook method from the wxPython module allows you to show a lot of data in a limited window space. It brings up tabbed pages you can click on to open each page. Enough said, run the code and experience the possibilities this humble method gives you.

This is another GUI program using the Tkinter module. It shows you how to change the background and foreground color of a component/widget. In this case it is a button. The button itself is used to toggle the color selection via a color dialog box. Enough comments have been added …

I was looking for a somewhat meaningful and interesting example to explain the Python class to beginners. A room full of multilingual students makes this phrase translator a good choice. You can experiment with it and add more languages and phrases.

Python's Tkinter module can be used to create a Graphics User Interface (GUI). This sample code creates a windows type form and positions a label and a canvas on the form. A simple shape is drawn on the canvas.

A common way to represent an inventory is with a list of tuples. Each tuple represents the item name and the item count. You can sort this inventory list by item name or item count. Here is an example to pick a sort key. It's your summer job to run …