Monthly Archives: July 2018

Get a weather forecast from openweathermap.org in C#

Posted on July 30, 2018 by RodStephens

This example displays a weather forecast from openweathermap.org. To get a forecast or other data, you build a URL describing your request and navigate to it. You then parse the returned XML or JSON data to see what openweathermap.org has … Continue reading →

Posted in internet, web, XML | Tagged , , , , , , , , , , , | Leave a comment

Draw rose curves in C#

Posted on July 27, 2018 by RodStephens

A rose curve is a curve generated by the polar coordinate equation r = cos(n / d * θ). Here n and d should be relatively prime, so the fraction n / d cannot be simplified. When you click the … Continue reading →

Posted in algorithms, drawing, graphics, mathematics | Tagged , , , , , , , , | Leave a comment

Find two sets where the median of one is the mean of the other and vice versa in C#

Posted on July 23, 2018 by RodStephens

For an upcoming book, I wanted to find sets where the mean (average) of one is the median (middle value) of the other and vice versa. I wanted to avoid trivial examples such as {1, 1, 1} and where the … Continue reading →

Posted in algorithms, combinatorics | Tagged , , , , , , , , , , | Leave a comment

Trim images in C#

Posted on July 19, 2018 by RodStephens

This example shows how you can trim images to remove unnecessary whitespace around their edges. Sometimes when I make pictures for a book, it’s hard to tell where the edges of the picture begin, so I risk either including more … Continue reading →

Posted in Uncategorized | Tagged , , , , , , , , | Leave a comment

Find Mersenne primes in C#

Posted on July 16, 2018 by RodStephens

Mersenne primes are prime numbers of the from 2n – 1 for some integer n. For example, 22 – 1 = 4 – 1 = 3 and 3 is prime, so 3 is a Mersenne prime. This example uses a … Continue reading →

Posted in algorithms, mathematics | Tagged , , , , , , , , , | Leave a comment

Display a progress bar with text in WPF and C#

Posted on July 12, 2018 by RodStephens

As is so often the case in WPF, the solution is simple after you spend a few hours figuring out what controls to use. This example uses a normal Grid control that holds a StackPanel. The following code shows the … Continue reading →

Posted in controls, user interface, wpf, XAML | Tagged , , , , , , , , , , , , , | 1 Comment

Convert between ragged arrays and two-dimensional arrays

Posted on July 10, 2018 by RodStephens

Ragged arrays are arrays that hold other arrays, as opposed to two-dimensional arrays. They are called “ragged arrays” because they work like two-dimensional arrays (or higher-dimensional arrays) where each row in the array can hold a different number of elements. … Continue reading →

Posted in algorithms, arrays, extension methods, generic | Tagged , , , , , , , , , , , | Leave a comment

Perform image hashing in C#

Posted on July 6, 2018 by RodStephens

Image hashing or (perceptual image hashing) attempts to reduce an image to a concise code that represents the image so you can compare it to other images to see if they are the same. This example uses a difference hash … Continue reading →

Posted in algorithms, graphics, image processing | Tagged , , , , , , , | Leave a comment