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 …

Read More

Here's a short shiny app along with some css that allows a font-awesome icon to behave as a checkbox. The font-weight setting in the css file determines if the icon should be solid (font-weight = 900 for TRUE) or regular (font-weight = 400 for FALSE). checkbox.css 1.fancy-checkbox input[type="checkbox"] { 2 …

Read More

Here's an example of using R to extract tabular content and metadata from a series of pdf files and push the data into a single table. The concept is fairly straightforward - read in PDF and convert to text, parse each line and use regular expressions to extract pertinent information. Three types of data are returned: …

Read More

I work with a single server and hence cannot set up a dev, test, prod environment. We also cannot use CI/CD and so I've developed a particular way of working under these constraints. All code is stored under a codes folder, residing under the home folder. The folder structure of the app is shown below and subfolders …

Read More

visNetwork is a fantastic library used to make interactive network graphs in R. It has many features to style nodes and edges but lacks a way to fill nodes using a continuous variable. ThIs can readily be achieved by using findInterval to map a continuous variable to the closest color on a color scale. In the example …

Read More

The sendSweetAlert function from the shinyWidgets package is a great way to communicate behavior to an end-user. As of version 0.4.9 shinyWidgets now uses SweetAlert2 which is no longer compatible with Internet Explorer thus breaking historical apps which use this feature. This is due to the fact that IE does not …

Read More

Formattable is a powerful R library used to format tables. There are many built-in functions which allow a user to style tables using color, bars ad icons. In addition you can create your own custom formatters. Below is an example of how to color a data frame using information from a second data frame. Average values …

Read More

RStudio Server is a fantastic IDE. Amongst its numerous features is the STOP button which allows execution to be halted. This works well in most instances but there are times when its use can cause a session to hang, in particular when the interrupted code is running a C function (this is a behavior of R rather than …

Read More

Using parseQueryString in conjunction with session$clientData$url_search can be used to pass variables to a shiny app from the url address. It can also be used with Sys.getenv('SHINY_PORT') to follow programming paths based on variable values and execution environment. In the example below, the code points to different …

Read More

Sometimes it's useful to mimic a button press in a shiny app when the Enter key is pressed, for example when entering a password. This has been documented before and works well for most situations but fails when the button widget is housed within renderUI. Here's an alternative that works wherever the password input …

Read More