CSC151.01 2015F, Class 23: Revisiting Lists =========================================== * Continue partners! Pick a new computer since we're in a new room. _Overview_ * Preliminaries. * Admin. * Upcoming Work. * Extra Credit. * Questions. * Lab. Preliminaries ------------- ### Admin * Apologies for the bad design of this room. * Thanks for finding the new classroom. We may be in this room tomorrow, too, depending on the state of the elevator. * EG complained that I don't bring you enough food. * DON'T ABUSE THE ART! * Reminder: We've thrown a *lot* at you this semester. * At least 100 vocabulary terms * Some syntax * A variety of concepts - some explicit, some that come from your assignments * **It's okay to ask questions, even on exams!** I can choose whether or not to answer. * Upcoming review sessions * Wednesday at 8pm (Zachary) * Thursday at 10am (Sam) * Thursday at 8pm (Caleb) ### Upcoming Work * Reading for Wednesday: [Recursion Basics](../readings/recursion-basics-reading.html) * Warning! For some, this will be even more confusing than `section`. For others, it will be intuitive. We will spend a few weeks trying to make it intuitive for everyone. * [HW 5](../assignments/assignment.05.html) due tonight. * Today's Lab writeup (due before class Friday) * Email to * Subject: _CSC 151 Lab Writeup Class 23 (Your Names)_ * Exercise: * [Exam 2](../assignments/exam.02.html) distributed. * We'll go through it quickly. * Probably lots of opportunities for corrections :-) ### Extra Credit Opportunities * If possible, send me these in advance. #### Academic * Any visit to the current show in the Faulconer gallery * CS Table today: Barbie and the "Internet of Things" * CS Extras Thursday: Blake Creasey on Watson #### Peer Support * Pals of PALS, pals@grinnell.edu, normally Saturday at 7:45 am (breakfast included), Sunday at 4:45, and Mondays at 4:45. Requires sign up in advance. * Pun Club, Saturdays, 4pm, Way over Younker. ### Other Good Things * Friends of Drake Library book sale this weekend. Community room. Friday 5-8 pm. Saturday 8am-2pm. Admission $3 on Friday and $0 on Saturday. HC $1, PB $0.50. Books usually $1/box after some time on Saturday (noon?). ### Questions _Should #2 work on any function?_ > Yes, those were just examples. _Does our procedure *have* to bound the y values?_ > No. You can assume a 100x200 window. _What's the difference between `left` and `column`?_ > `left` represents the left edge of an area. It's a column, but columns can take on other values. _When I'm picking the random column and row, what range should I choose from?_ > For the column, it should be a number between left and left+width-1. _But `random` only gives me a value between 0 and n-1._ > Think about how to transform one range to another. (Hint: Addition.) _Do I need to document the procedures in part 3?_ > Yes. But you can use just 4P's. Lab --- * Important lesson 1: If you have something you think is a list, and you see a dot in the middle of it, it's not a list, and at some point things will probably break. * Important lesson 2: `car` and `cdr` don't care whether or not it's a list, as long as it's created by `cons` (or is a non-empty list) * (car (cons a b)) = a * (cdr (cons a b)) = b * Important lesson 3: Computer scientists usually count starting at 0 (for cardinal numbers) * The first element of a list is element 0 * The second element of a list is element 1 * No writeup, but you need to make sure you understand this stuff. It's essential for the rest of the semester.