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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I don't know why this took so long but I finally switched this blog from Jekyll to Hugo. Not that there's anything wrong with Jekyll but I've been experimenting with Hugo a lot over the last year and I feel more comfortable with it. This is built on the clarity theme, a beautiful theme for blogging.

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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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Chemistry scale-up labs tend to have multiple pieces of equipment connected to a single reactor. These items can work indepentently, co-dependently or fully-dependently with respect to each other. Automated reactors have been in existence for a number of years. These systems can generally collect and store data for a …

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In order to test communication we'll set up two clients, each representing an instrument, along with a server which acts as the MQTT broker, database and visualization. The three machines are all running ubuntu under VirtualBox. In this case client1 sends measurement1 data which resets to a random value between 20 and …

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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 …

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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: …

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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 …

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