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 …

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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 …

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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 …

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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 …

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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 …

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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 …

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I have to post this for my own sanity. I tend to create shiny apps in a specific folder and link to them using symbolic links from the ShinyApp folder. This allows multiple versions (prod and dev) and keeps code clean. I don't know how many times I've wrestled with an app pointing to an earlier version when updates …

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Using shiny modules a large shiny application can be broken down into manageable chunks. Modules work well with most aspects of shiny code but care needs to be taken when referencing inputs. This is especially true when javascript is used within a module. Here's a piece of code which uses a callback in a datatable to …

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This year I'm trying out slack as a platform for out fantasy football league. It provides channels for banter, keeping track of transfers and, with the use of rss feeds, up to date information. In addition I've set up a channel dedicated to injuries tied to an incoming webhook. The injury channel works by running a …

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Method One - Does not work with IE CSS variables are a powerful way to make wholesale changes to the style throughout an entire document. They are set using a custom notation --variable_name and accessed throughout the document using var(--variable_name). With a little javascript these variables can be used in Shiny …

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