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Category: R

Alt Text in R

Published 2023-03-24 by Kevin Feasel

Nicola Rennie looks at different ways to incorporate alt text in R-based images:

Alt text (short for alternative text) is text that describes the appearance and purpose of an image. Alt text has multiple purposes, the main one being that it aids visually impaired users to better understand your content when the alt text is read aloud by screen readers. Alt text is also used in place of an image if it fails to load, which means that users with poor internet connection are more likely to be able to engage with your content.

The ggplot2 example was an interesting one, as I hadn’t ever added alt text to an image there.

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Estimating Simulation Variance when Running Stan Models in R

Published 2023-03-23 by Kevin Feasel

Sebastian Sauer takes a look at an interesting question:

stan_glm() allows for setting a seed value thereby eliminating the variance induced by random numbers. However, in case a seed is not used, how much variance is to be expected? This is the research question of this analysis.

Let’s choose n=100 repetitions in our simulation.

Click through for the demonstration, including a summary table and notes on installed packages for the sake of reproducibility.

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Building a Shiny App to Show Star Maps

Published 2023-03-23 by Kevin Feasel

Benjamin Smith builds a UI:

Recently, I released a R package called starBliss that aimed to replicate the output of a e-commerce site called MapsForMoments – a site which lets users order custom prints of the night sky on the date of their choosing (usually a special occasion such as a birthday, first date, wedding etc.) and allows them to choose a style, and add some custom text. It was a great experience getting to build the package which replicated the MapsForMoments product and I was shocked to see how well it was received when I posted about it- with the Github receiving over 30 stars at the time of writing this blog!

I decided to take this to the next level by trying to build a similar UI in shiny which allows the user to create a custom star map and not need to use the R console. In this blog I share my experience constructing and showcase the “free alternative” to MapsForMoments – starBlissGUI!

Click through to see how you can run the app, as well as a sample output.

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Customizing Shiny Apps with shinydashboard

Published 2023-03-17 by Kevin Feasel

Mandy Norrbo isn’t satisfied with the defaults:

Using {shinydashboard} is great for creating dashboard prototypes with a header-sidebar-body layout. You can quickly mock up a professional looking dashboard containing a variety of outputs, including plots and tables.

However, after a while, you’ll probably have had enough of the “50 shades of blue” default theme. Or, you might have been asked to to follow company branding guidelines, so you need to replace the default colours with custom ones.

Click through for a walkthrough of what is available for customization and how to do it.

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The apply() Family in R

Published 2023-03-13 by Kevin Feasel

Steven Sanderson operates over a list of operators over lists:

In this post I will talk about the use of the R functions apply(), lapply(), sapply(), tapply(), and vapply() with examples.

These functions are all designed to help users apply a function to a set of data in R, but they differ in their input and output types, as well as in the way they handle missing values and other complexities. By using the right function for your particular problem, you can make your code more efficient and easier to read.

I do prefer the purrr() syntax because it’s a little easier to remember its function names versus keeping the variants of apply() straight in your mind. Even so, there’s a lot you can do with a judicious use of apply().

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Tracking Network Errors with WASP

Published 2023-03-09 by Kevin Feasel

Thoe Roe gives us an introduction to Network Error Logging:

Heads up! We’re about to launch WASP, a Web Application Security Platform. The aim of WASP is to help you manage (well, you guessed it) the security of you application using Content Security Policy and Network Error Logging. We’ll be chatting about it more in a full blog post nearer the time.

Read on to learn about what Network Error Logging is, how you can activate it for a website, and what information you get back as a result.

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Tracking Home Heating Oil Prices in R

Published 2023-03-09 by Kevin Feasel

Steven Sanderson charts some prices:

If you live in New York and rely on heating oil to keep your home warm during the colder months, you know how important it is to keep track of heating oil prices. Fortunately, with a bit of R code, you can easily access the latest heating oil prices in New York.

The code uses the {dplyr} package to clean and manipulate the data, as well as the {timetk} package to plot the time series.

Read on for an overview of what the code does, followed by the code itself and a time series plot at the end.

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pmap and imap Examples in purrr

Published 2023-03-07 by Kevin Feasel

Steven Sanderson has a multi-parter for us. First up is a look at the pmap() function in R’s purrr library:

The pmap() function in R is part of the purrr library, which is a package designed to make it easier to work with functions that operate on vectors, lists, and other types of data structures.

The pmap() function is used to apply a function to a list of arguments, where each element in the list contains the arguments for a single function call. The function is applied in parallel, meaning that each call is executed concurrently, which can help speed up computations when working with large datasets.

Next up is the imap() function:

The imap() function is a powerful tool for iterating over a list or a vector while also keeping track of the index or names of the elements. This function applies a given function to each element of a list, along with the name or index of that element, and returns a new list with the results.

The imap() function takes two main arguments: x and .f. x is the list or vector to iterate over, and .f is the function to apply to each element. The .f function takes two arguments: x and i, where x is the value of the element and i is the index or name of the element.

Both of these sound a little complex and abstract at first, though as you get more familiar with them, you get to see just how powerful they are.

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Content Security Policies and Posit Connect Apps

Published 2023-03-02 by Kevin Feasel

Theo Roe gets into some web security:

Heads up! We’re about to launch WASP, a Web Application Security Platform. The aim of WASP is to help you manage (well, you guessed it) the security of your Posit Connect application using Content Security Policy and Network Error Logging. More details soon, but if this interests you, please get in touch.

This blog post is aimed at those who are somewhat tech literate but not necessarily a security expert. We’re aiming to introduce the concept of Content Security Policy and teach some of the technical aspects.

This does provide a nice overview to the topic and explains the key “what” and “why” answers.

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