Python autograder to facilitate code output and static code checking.
Project description
pygradethis
A Python package to facilitate checking code output or static code checking
using AST analysis. It can either be used with R using the learnr
package, as
a mirror of gradethis
package, or as a standalone package for general Python
use in educational settings.
Note: This package is in early development and will undergo rapid changes.
Install pygradethis
pip install pygradethis
Install Dev Dependencies
pip install -e .[dev]
Features
- Simple output checking based on pass / fail conditions with feedback
- Simple static code checking (AST), with feedback on how student's code differs from solution
Output checks
pygradethis
mimics the cadence to gradethis::grade_result
. For e.g., we can
check that the student supplies the mpg
dataset like so:
grade_result(
pass_if_equals(mpg, "You also got the mpg dataframe!"),
fail_if_equals(None, "")
)
Internally, these pass_if_equals(output, message)
or fail_if_equals(output, message)
will be checked sequentially in
the order of arguments and return on first condition we match. The None
here can be used
if you simply want to execute a condition if none of the other conditions matched.
If we match a pass_if_equals
or fail_if_equals
, we will present a feedback message wrapped in a convenient dict
:
dict(
message = str,
correct = True|False,
type = "auto|success|info|warning|error|custom",
location = "append|prepend|replace"
)
The message
is the feedback, the correct
is whether or not the student's solution is correct, type
is the type of feedback. When
used with learnr
the location
field here is useful for where the message is situated in the tutorial. However, for those using
this package as a standalone the location
is not an important field and it can be ignored. More on the flags here.
Internally, a random praise/encouragement message will be appended before any custom message supplied.
pass_if_equals(x = mpg, message = "You also got the mpg dataframe!")
Feedback:
Bravo! You also got the mpg dataframe!
fail_if_equals(x = None, message = "")
Feedback:
Try it again. You get better each time.
Code checks
For static code checking, we follow a similar cadence for gradethis::grade_code
.
When there is a solution code being supplied, grade_code(user_code, solution_code)
can be used to check the AST of
the user and solution code, making sure to standardize function calls and producing a helpful message for the student
to diagnose their issue.
Example:
grade_code(
student_code="2 + sqrt(log(2))",
solution_code="2 + sqrt(log(1))"
)
Feedback:
I expected
log(1)
, but what you wrote was interpreted aslog(2)
insqrt(log(2))
at line 1.
Note how the feedback narrows in on the expression in which the problem occurs (sqrt(log(2))
)
so that the student can focus on the most relevant outer expression of the problem. In this case, the
log(2)
is the problem and the 2
on the left operand of
the addition is not as relevant.
Similarly, here the feedback points out that the 2 within the log
function is incorrect, similar to the
gradethis
example.
Call Standardization
pygradethis
also knows how to take user's function call code and map positional arguments
to proper parameter names and set defaults if not supplied. This is so that you don't penalize
a student's code just because they did not explicitly spell out positional argument names, or
write the default arguments out.
For e.g. suppose a student is calling the following silly function foo
:
def foo(a, b=1):
pass
Grading the code with
grade_code(
student_code="foo(1)",
solution_code="foo(1)"
)
In the example above, the grade_code
doesn't give us a feedback message since they are equivalent expressions.
However, if the student supplies foo(2)
grade_code(
student_code="foo(2)",
solution_code="foo(1)"
)
we get back this feedback:
I expected
1
, but what you wrote was interpreted as2
infoo(2)
at line 1.
Note: Although underneath the hood we do standardize the arguments of both the student and the solution code
before checking, we don't surface this standardized form to the feedback message. This is certainly possible to
achieve but in certain cases can hinder learning by revealing too much information. For example, the builtin functions
like sum
is normally called without specifying its actual formal parameters (e.g. sum(1)
versus sum(iterable=[1], start=0)
. In the future, a verbose
mode could be made available such that the formal parameters are pointed out.
For call standardizing to work, the function definitions corresponding to function
calls must be defined and 'live' in the environment, whether that is the globals()
/locals()
,
builtins
, or custom module imports pandas
. This works if the student/solution source code also
includes the definition (like foo
above) in their own source code or it's included by instructor.
Currently, common modules like math
is imported for grading within check_functions.py
, but more modules
will be included to serve data science grading as well, such as pandas
or numpy
in the future.
We plan to make the code more extensible for the instructor to add them as dependencies.
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