Develop a function add-dots which
takes in an image and a list of posns, and returns the image with dots at
each of those positions. For example,
(define SIDE 100) (define box (move-pinhole (rectangle SIDE SIDE "outline" "black") -50 -50)) ... (add-dots box (list (make-posn 15 12) (make-posn 25 47)))
Type the following struct definition into your definitions window:
(define-struct employee [name salary id])(Recall that I used this definition to write
total-salary
in class. Review this function and its examples before going on.)
We'll be working with lists of employees; call this the
"employee-list" data type.
Develop the following functions:
count-over-100K, which takes a list of employees and tells how many of them have a salary over $100,000.fire-highly-paid, which takes a number and a list of employees and returns a new list of employees, leaving out the ones who earned over the specified amount. (Note that this is a generalization offire-over-100K.)sort-by-salary, which takes a list of employees and returns a list of the same employees sorted by salary, from lowest-paid to highest-paid.
Develop a function named
"table-of-squares" which takes in a natural
number
n and produces a list of posns, associating
each of
the numbers 1...n with its square. For example,
(table-of-squares 5)(list (make-posn 5 25) (make-posn 4 16) (make-posn 3 9) (make-posn 2 4) (make-posn 1 1))Note: I've put these in descending order because it's easier to write the function that way. For extra credit, produce the table in increasing order.
Recall the
random-posn function from homework 4.
Develop a function named
"random-posns" which takes in a natural number
n and two other numbers
max-x and max-y, and produces a list of that many
posns, each randomly chosen as in random-posn,
above.
add-dots.
Extra credit: do exercise 12.4.2.
Hint: You must read all of section
12.4
leading up to this problem before tackling it; otherwise you'll
misunderstand the question, solve the wrong problem, and get no credit.
Another hint: You'll need at least two auxiliary
functions.
For the next few problems, you'll need to set DrScheme to at least the "Intermediate Student" language level.
Review the function sort, discussed
in class on 19 April.
Develop a generalized function
general-sort which takes a non-empty list of X's (where X is
any data type) and a function (let's call it
beats?)
with the contract "X X -> boolean", and returns a list of the
same objects, sorted in order so that each element "beats?"
the one after it. For example,
(general-sort < (list 5 2 4 6 3)) "should be" (list 2 3 4 5 6) (general-sort > (list 5 2 4 6 3)) "should be" (list 6 5 4 3 2)Note: You'll need an auxiliary function. For full credit, put this auxiliary function inside a local definition.
Re-write sort-by-salary using
general-sort. Your new definition should fit on four or
five reasonably short lines.