One of my all-time favourite open source tools is Open Refine, which "is a powerful tool for working with messy data: cleaning it; transforming it from one format into another; and extending it with web services and external data." Today I'm talking about that extending bit. One of the nice features of Open Refine is that it can run on Linux, Windows, or MacOS. I only have experience with the latter two, but am pretty sure what follows applies to Linux as well.
So here it is in a nutshell. When you install an extension in Open Refine, sometimes there will be an indication in the upper right of your Open Refine page that the extension is installed, but just as often there is no indication other than a new choice within a drop-down, or a new function that's now available in GREL. I think maybe the first few extensions I ever installed resulted in a drop-down choice in the upper right, so I made the assumption that's how all extensions behaved. I'm embarrassed to tell you how much time I have wasted installing, uninstalling, then trying a different location all in vain as I restarted Refine only to not see the expected shiny new extension greeting me in the upper right corner.
How many extensions do I have correctly installed here? (The pull-down only relates to the named extension you see)
Wrong - I have four installed! Until earlier today I too would've sworn it was only one, but these other three operate elsewhere within the program, either through a drop-down, or as part of GREL:
And how did I finally figure this out? I finally read the frickin' readme file within one of those extension folders and it explained all. Hope this helps someone else out there. I've gone ahead and clarified the instructions on how to install extensions as well.
As an aside, if you haven't looked at it lately, Open Refine seems to have a new lease on life, with a couple of recent point releases and a new push on looking for new contributors (even non-coders).