Using R script to generate answer values

[Swidbert Ott]

Hi all,

I'm new to Numbas and probably getting ahead of myself ... but here is what I'm hoping to do in a nutshell: run R code (written by me, not submitted by student) to drive the answers to either numeric or SBA questions. The context is students working through a guided data analysis in their own time, and answering questions in the "exam" as they go along.

I'm failing at the first hurdle, as it were; I've tried to use a trivial bit of R to define a Numbas variable, thus:

- a "string" variable called myRcode, with my R code

- a "JME code" variable, value set to `run_code("webr", myRcode)'

- `Programming` extension enabled under "Extensions & scripts"

Admittedly, I don't even understand yet how the R output would be interfaced with the "JME code" variable, but I don't get that far because the JME code variable doesn't know about the run_code() function:

Error evaluating variable code_runner: No definition of 'run_code' of correct type found.

I'm aware of the "Code" type question part, but my understanding is this isn't what I need.

Any help appreciated - including RTFM with a pointer to the right manual; I'm struggling with https://numbas.mathcentre.ac.uk/extensions/253/documentation

Many thanks, Swidbert

[Christian Lawson-Perfect]

Hi Swidbert,

At the moment, I don't think you can use R to generate a value used in a question variable. 

R code can only be run asynchronously - you ask for the code to be run and then the result comes back at some unknown time in the future - while the variable generation code expects everything to complete synchronously. It's a limitation that I'd like to remove at some point, but it'll need a big change to how question variables are generated.

Whatever you're asking R to calculate, you'll have to do it in JME instead. If you can describe what data you need to generate, I can try to give some advice about how best to do it.

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