I’ve been having problems with the web version of the Open-Meta app crashing with a
C stack usage error. I entered an issue on the Shiny Server Github page and with the help of others who have had this problem, now suspect that the error is caused by the rJava package, which is required by mailR, the package I’ve been using to send email.
Continue reading “LEMRS v0.5 – Adding rvest and aws.signature”
observeEvent() handler for all your button and anchor clicks. This week I needed disabled buttons, which are easy to do visually by adding the Bootstrap
disabled class to the button. But the buttons still responded to being clicked.
Continue reading “Shiny button observer update: ignoring clicks on disabled buttons”
MySQL provides an external program called mysqldump that writes a file full of MySQL syntax statements that will recreate a database’s tables and their contents. Back in the Apple II days this kind of file was called an exec file. Windows calls them batch files and Linux calls them shell scripts, of which one common format is the bash file. You can create the same thing with HeidiSQL by right-clicking on the database you want to save or duplicate and selecting Export database as SQL.
Continue reading “How to source a mysqldump file with syntax statements”
Who knew? I thought the difference between
&& for ANDing logical vectors in R was just that
& evaluated the whole expression while
&& started at the left and went right until it hit a
FALSE value. But there’s more.
& is vectorized, but
&& only considers the first value in a vector and only returns a single value.
Continue reading “Why is my logical && comparison producing NA?”
Today I created a new instance for the open-meta.org app on Amazon. Mostly this was to add the RCurl package to R, which I needed to access the PubMed utilities online now that they require
https:// rather than
Continue reading “LEMRS v0.4 – Adding RCurl Package”
The Tidyverse is a collection of related R packages, many of which I use on Open-Meta. I recently added the entire Tidyverse to my Windows-based development system, which meant I had to do the same to move that code to my Amazon Lightsail instance, which I did yesterday.
Continue reading “Let’s put the whole Tidyverse on Amazon Lightsail (LEMRS v0.3)”
invalidateLater() function, if you know about it at all, probably doesn’t work the way you think it does. Moreover, the way it actually does work, it turns out, is way cooler than the way it appears to work!
Continue reading “How Shiny’s invalidateLater() actually works”
<a id="xxx">). Anchor tags are typically used to create links and include an href attribute that holds the URL of the linked document.
Continue reading “Adding anchors to our Shiny button observer”
One of the profound limitations of Shiny is the way it supports buttons. Buttons are based on a function called actionButton(). When a button is clicked, Shiny reports the click on input$button_id. Every button has to have a unique id, which means that each button also has to have its own observer to watch for a click. But what if you want to do something like this:
Today I decided to try adding the RStudio Server to my Amazon Lightsail instance. There are three steps to this – downloading and installing the software, opening up port 8787, and adding a user with a password who can log in to the server.
Continue reading “Adding RStudio to an Amazon Lightsail Instance”