Technology Tales

Clearing the Julia REPL

23^rd September 2024

During development, there are times when you need to clear the Julia REPL. It can become so laden with content that it becomes hard to perform debugging of your code. One way to accomplish this is issuing the CTRL + L keyboard shortcut while focus is within the REPL; you need to click on it first. Another is to issue the following in the REPL itself:

print("\033c")

Here \033 is an escape code in octal format. It is often used in terminal control sequences. The c character is what resets the terminal to its initial state. Printing this sequence is what does the clearance, and variations can be used to clear other kinds of console screens too. That makes it a more generic solution.

Dropping to an underlying shell using the ; character is another possibility. Then, you can use the clear or cls commands as needed; the latter is for Windows systems.

One last option is to define a Julia function for doing this:

function clear_console()
    run(`clear`)  # or `cls` for Windows
end

Calling the clear_console function then clears the screen programmatically, allowing for greater automation. The run function is the one that sends that command in backticks to the underlying shell for execution. Even using that alone should work too.

Removing a Julia package

5^th October 2022

While I have been programming with SAS for a few decades, and it remains a linchpin in the world of clinical development in the pharmaceutical industry, other technologies like R and Python are gaining a foothold. Two years ago, I started to look at those languages with personal projects being a great way of facilitating this. In addition, I got to hear of Julia and got to try that too. That journey continues since I have put it into use for importing and backing up photos, and there are other possible uses too.

Recently, I updated Julia to version 1.8.2 but ran into a problem with the DataArrays package that I had installed, so I decided to remove it since it was added during experimentation. Though the Pkg package that is used for package management is documented, I had not got to that, which meant that some web searching ensued. It turns out that there are two ways of doing this. One uses the REPL: after pressing the ] key, the following command gets issued:

rm DataArrays

When all is done, pressing the delete or backspace keys returns things to normal. This also can be done in a script as well as the REPL, and the following line works in both instances:

using Pkg; Pkg.rm("DataArrays")

While the semicolon is used to separate two commands issued on the same line, they can be on different lines or issued separately just as well. Naturally, DataArrays is just an example here; you just replace that with the name of whatever other package you need to remove. Since we can get carried away when downloading packages, there are times when a clean-up is needed to remove redundant packages, so knowing how to remove any clutter is invaluable.