EBoard 07: Cut and compose (Section 1)
Today’s start-of-class procedure
Plan to sit with your partner from last class (in the same place).
Warning! You are being recorded and transcribed, provided the technology
is working correctly.
Approximate optimistic overview
- Administrative stuff [10 min]
- Some academic integrity issues [5 min]
- About Wednesday’s quiz [5 min]
- About reducing redundancy [5 min]
- About MP3 [15 min]
- Questions [5 min]
- Lab [30 min]
- Turn in lab [5 min]
Administrative stuff
Introductory notes
- Sam forgot his hearing aids today. Expect him to have even more trouble
than normal.
- Please try to avoid putting images and colors in the definitions pane.
When you do so, your Racket file ends up saving in a strange format that
doesn’t work with Gradescope. Yay computers!
- I’d also recommend that you do without
image-load and image-save in
the definitions pane.
Upcoming activities
Scholarly
- Thursday, 13 February 2025, 11:00 a.m.–Noon, JRC 101.
Grinnell Lecture: Darrius Hills on “The Achievement of Identity: Soul Work, Salvation, and Black Manhood in the Religious Imagination of James Baldwin”.
- Tuesday, 18 February 2025, Noon–12:50 p.m., PDR 224C (White Dining Room).
CS Table: ???
Artistic
- Friday, 7 February 2025, 3:00–5:00 p.m., Burling Digital Studio.
Make a Fidget Workshop.
- Tuesday, 11 February 2025, 4:00–5:00 p.m., Bucksbaum 131 (GCMoA).
Gallery Talk with Chen, Kluber, and Tavares.
- Friday, 14 February 2025, 5:00–6:30 p.m. (talk at 6:00), 926 Broad St (Stewart Arts Building).
Opening Reception for Artist Salon: Works by Grinnell College Art Majors
Multicultural
- Friday, 7 February 2025, 4:00-5:00 p.m., HSSC N1170 (Global Living Room)
Middle of Everywhere: How to Order a Coffee in Singapore.
Peer
Musical, theatric, sporting, and academic events involving this section’s
students are welcome.
- Saturday, 2025-02-08, 1:00–3:00 p.m., Natatorium.
Swimming Last Chance Meet
Wellness
- Friday, 7 February 2025, 5:30–8:00 p.m., Downtown Grinnell.
The Sweet Stroll.
- Tuesday, 11 February 2025, 12:15–12:50 p.m., GCMoA.
Yoga in the Museum.
- Tuesday, 11 February 2025, 4:30–6:30 p.m.,
BRAC P103 (Multipurpose Dance Studio).
Wellness Yoga.
Misc
- No particular date. Cyberspace.
Fill out the survey at https://www.surveymonkey.com/r/GrinnellParksandRec.
- Sunday, 9 February 2025, 7:30–8:30 p.m., Science 3819.
Mentor Session.
- Tuesday, 11 February 2025, 7:00–8:00 p.m., Science 3820.
Mentor Session.
- Tuesday, 18 February 2025. 6:00–7:00 p.m., HSSC A1231.
Make a Portfolio Website.
Other good things
These do not earn tokens, but are worth your consideration.
- Saturday, 2025-02-08, 1:00–3:00 p.m., Darby.
Women’s Basketball vs. Lake Forest
- Saturday, 2025-02-08, 3:00–5:00 p.m., Darby.
Men’s Basketball vs. Lake Forest
Upcoming work
- Friday, 2025-02-07 (today)
- Sunday, 2025-02-09
- Tuesday, 2025-02-10
Friday PSA
- You are awesome.
- People care about you.
- Please, try to keep yourself awesome.
- Moderation!
- Plan in advance! Remember that everyone has different limits.
- Consent is essential, but not sufficient.
Academic Integrity
Example one: A student comment from mini-project 2.
For the pentagon, I did get a little bit of help from the programming
assitant chatgpt, I was having trouble with knowing how to incorporate
real-part, imag-part, and tying it all together.
- Thanks for citing.
- However, Do not use AI programming assistants!
- Ask a human being. Don’t ask the computer.
- Reminder
- Mentor sessions are class specific and often focus on forthcoming quiz and
past material.
- Evening tutor sessions provide individual help on homework and such.
Example two: Some code from mini-project 2
(build-list sides (lambda (i) (make-point side-length (general-radius sides) (general-theta sides) (+ 2 i))))))
- Hmmmm … I haven’t taught you
build-list. So the student found it on the
Interweb. (Hopefully not with ChatGPT.)
- Let’s see where (of course, they cited it).
- Nope.
- In general, I’d prefer that you not go far beyond what we’ve learned
in class.
- If you do, plese cite!
Example three: Strange file uploaded
- Make sure to check the autograder!
About Wednesday’s Quizzes
There are many goals and processes for decomposition. Not only are we
breaking a big problem into smaller parts, we are also trying to avoid
repeating ourselves.
In many cases, I saw that you did some decomposition well, but left some
repeated code. My initial inclination was to mark all of those as “Redo”.
After some reflection, I decided that talking about it in class would suffice.
If there’s more than one case of repetition, you have a redo. If there’s
only one, you have an S.
On to the problem itself …
About reducing redundancy
Sam, how do I reduce redundancy in my compute-pentagon-point procedure?
(define compute-pentagon-point
(lambda (radius num)
(pt (real-part (make-polar radius (* 2/5 num pi)))
(imag-part (make-polar radius (* 2/5 num pi))))))
- First of all, great job on using the radius, rather than the side length,
so that you don’t have to duplicate the conversion of side length to
radius!
- Second, TPS!
Possibility one
(define part-of-compute-pentagon-point
(lambda (radius num)
(make-polar radius (* 2/5 num pi))))
(define compute-pentagon-point
(lambda (radius num)
(pt (real-part (part-of-compute-pentagon-point radius num))
(imag-part (part-of-compute-pentagon-point radius num)))))
Possibility two
(define polar->point
(lambda (polar)
(pt (real-part polar)
(imag-part polar))))
(define compute-pentagon-point
(lambda (radius num)
(polar->point (make-polar-radius (* 2/5 num pi)))))
Key ideas here:
- If you have a bigger procedure with repetition, think about defining a
separate procedure for the different parts.
- Reduce complexity by writing procedures that produce other types of
values.
- If you have a value that you are computing multiple times, create another
procedure and pass that value to the next procedure.
- Eventually, we’ll learn how to name things within a procedure.
About Mini-Project Three
Fun with transformations.
Q&A
Administrative
Do I have to tell you when I’m spending a token to turn something in late?
No.
I got an I on MP1. Will you charge me tokens for redoing MP1?
No.
I got an I on MP2. Will you charge me tokens for redoing MP2?
Yes. Tokens are my way of encouraging you to make sure you make an
appropriate start on mini-projects.
When do we make up quizzes?
Option 1: During the next quiz day, there will (usually) be make-ups
for past quizzes. (They aren’t identical.)
Option 2: On the SoLA (take-home exams).
Can you tell us more about take-home exams?
Yes, when I distribute them. But not today.
Is it okay that I learned things from the Racket Web site and cited them?
Yes.
When redoing a mini-project do I have to start over?
Generally, no. Just fix the parts that we tell you need fixing.
Readings
Lab
Same partners, new submission
Q: How did you expect us to write rgb-less-red?
A: I was expecting (o rgb-pseudo-complement rgb-redder rgb-pseudo-complement),
but (o rgb-greener rgb-bluer) seems to work, too.