How to setup
nbgrader for CoCalc to work with
There are plenty of examples of creating assignments for
Python. For other languages, not so much.
I couldn’t find any for
R. To get
R to work, you need to add one line to the default
nbgrader_config.py file. Here is my file that I placed in
/etc/jupyter (on my own computer - have not gotten this to work yet on CoCalc):
The line that starts with
"R" enables using
R in creating the student release version.
nfail() is an
R function from the
R package that raises an error if the student does not provide an answer. It’s the equivalent to the
raise NotImplementedError call in the line for
Python. This config file has to placed somewhere
Jupyter can see it. On my own computer it is in
/etc/jupyter. We are still trying to figure out where it should go on CoCalc.
Note that you can see the paths for
Jupyter by typing at the command line:
How to prepare an assignment in CoCalc for
When you create an assignment for
nbgrader, you create the instructor version that includes the solution and a code cell that tests the solution.
When you create this version, you use the
View/Cell Toolbar/Create Assignment pull down menu to add the metadata to the solution code cell and the test code cell.
The Create Assignment view is an extension added by
(If you look at any Python example you will see similar cells.)
The test code cell assigns the number of points for the problem.
Need to add a link to an example R notebook
Until the link is added, here is an example of the
R code in a solution code cell:
cars <- ### BEGIN SOLUTION read.table("mtcars.csv",header=TRUE,sep=",") ### END SOLUTION
Here is an example of the corresponding
R code for the test code cell:
# Do not modify this code require(testthat) cars2 <- data.frame(car=rownames(mtcars),mtcars) rownames(cars2) <- NULL expect_equal(cars,cars2) print("Success!")
When you generate the student release version, the solution cell code between the lines
### BEGIN SOLUTION and
### END SOLUTION will be replaced by the code specified in the
nbgrader_config.py file for
# your code here nfail() # No Answer - remove if you provide an answer
(Note also that the comment delimiter is # for both
Python - this simplifies things for
R. If we were using a language that uses a different comment delimiter, then we also have to specify that somewhere in the config file.)
Note that in this example I’m using functions from the
R package. When you go to autograde the student assignments, if the solution is considered incorrect by your test code, an error is raised and this is noted by
nbgrader and handled accordingly. Other similar functions from similar packages of course could be used.