On 01May2019 19:22, britt...@gmail.com <britt...@gmail.com> wrote:
We have to populate a timetable with subjects. What would be the best
approach?
That's a pretty open ended question. Often a constraint on generating
timetables involves ensuring that no 2 subjects use the same timeslot if
a student might need to take both those subjects. Unless that student is
Hermoine Grainger.
Also, this looks like homework: we're happy to help, but we tend not to
write code for you. We'll suggest approaches and answer specific
questions.
But...
In our sample timetable there are 25 hours (keys), all the FH value should be
replaced with random subjects as many as their corresponding hour.
timetable = [{'A1': "FH", 'B1': "FH", 'C1': "FH", 'D1': "FH", 'E1': "FH"},
{'A2': "FH", 'B2': "FH", 'C2': "FH", 'D2': "FH", 'E2': "FH"},
{'A3': "FH", 'B3': "FH", 'C3': "FH", 'D3': "FH", 'E3': "FH"},
{'A4': "FH", 'B4': "FH", 'C4': "FH", 'D4': "FH", 'E4': "FH"},
{'A5': "FH", 'B5': "FH", 'C5': "FH", 'D5': "FH", 'E5': "FH"}]
subjects_required_hours = {"S1": 4, "S2": 3, "S3": 5, "S4": 3, "S5": 5, "S6": 5}
Given just the constraint you describe you want to do something like the
following:
loop over the keys of the timetable
for each key, pick a random subject from those available
fill in that timetable key with the subject
reduce the hour count for that subject by the length of the
timetable slot (1 hour, so just 1)
The definition of "available subjects" above will be those subject with
more than 0 hours.
You might do that in a few ways. Two examples:
Use "subject_required_hours" (or a copy of it) as your record of
available subjects. When a subject's hours drop the 0 (when you subtract
1 above), deleted it from "subject_required_hours" using the "del"
Python statement. That way the dict only contains available subjects. So
you just pick randomly from the keys of the dict on each loop iteration.
Alternatively you could treat it like a deck of cards: make an empty
list, and append to it sufficent copies of the subject names so that it
looks like:
["S1", "S1", "S1", "S1", "S2", "S2", "S2", "S3" .......]
Then in the loop pick a random element from the list, and remove that
element.
Performance note: deleting an element from anywhere but the end of a
list is a little expensive, so you might instead copy the last list
element to the "deleted" location, and delete the last element.
Python has a "random" module for getting random numbers and you can use
that to choose a random index into an array/list.
If you pick an approach and then encounter more problems, come back and
ask (by replying to this thread, _not_ by making a totally new message),
and include both your code and whatever output you're getting, along
with a description of what's wrong with the output. Always cut/paste
code and errors messages straight into your message - this list strips
attachments and non-text.
Cheers,
Cameron Simpson <c...@cskk.id.au>
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