Purpose Can we use use RStudio Connect to build an internal contact form on a {distill} website? {distill} is a great R library for building static websites and blogs but has the same limitations of other static websites, namely no server-side programming. This means that implementing a contact form requires using a …

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This is an initial concept of a framework for multiwindow shiny apps. Shiny is a great R package for building an interactive, web-based, graphical UI using R. It does, however, suffer from some limitations. One of these is the fact that a Shiny app runs in a single browser window. To make a more complex interface we …

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The {tidyselect} package powers column selection for {dplyr}, {tidyr} and {recipes} functions but it's also quite straight-forward to include its functonality in other user-built functions. Here's an example which replaces a percentage of a data frame by NA. It works by using the tidyselect::eval_select function to …

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magrittr is the pipe, commonly used in tidyverse packages, that enables simple sequencing of operators. The simple forward pipe replaces f(x, y) with x %>% f(y). Code becomes much more readable when chaining multiple pipes together. It’s very simple to use this in any package. the usethis package provides a command …

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Generally there is no issue in sending a list of parameters (reactive and non-reactive) to a shiny module. Here's an example where a shiny module would be called multiple times, programatically, where the reactive nature of the parameters may be variable (reactive in one instance but not in another). One way to deal …

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Examples of passing a list of reactives, reactiveValues list and reactiveValues to a shiny module. This helps explain reactivity when passing values to a shiny module. In each case we pass a value A which triggers mod A and value B which triggers mod B. The code below and output demonstrates which outputs in the shiny …

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The traveling salesperson problem (TSP) is an NP-complete problem that asks given a list of cities, what's the shortest path that can be taken so that each city is visited once and you end up back where you started. Exact solutions to the problem exist but they become impractical as soon as the number of cities …

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Programatically sending an email under Linux is relatively simple. There are several command line clients such as sendmail and mail which are very easy to use. There are also several R packages to help send emails such as {mailr} and {blastula}. Generally you need access to an SMTP to send messages programatically and …

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CAS numbers consist of three numbers separated by dashes. The first comprises of two to seven digits, the second is two digits and the third is one digit. The last number is, in fact, a check digit for the rest of the code. It's simple to check if a CAS number contains an error by calculating a checksum as follows: …

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It's relatively easy to extract CAS numbers from a PDF. I've used this to scrape chemical catalogs, subsequently using the CAS numbers to look up additional information through PubChem. CAS numbers are easier to scrape than most other chemical information, such as name, formula or catalog number, as they follow a …

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