CSC A20H3 S 2011 Test 1 Duration 90 minutes Aids allowed: none. Student Number:

Transcription

1 CSC A20H3 S 2011 Test 1 Duration 90 minutes Aids allowed: none Last Name: Lecture Section: L0101 Student Number: First Name: Instructor: Bretscher Do not turn this page until you have received the signal to start. (Please fill out the identification section above, write your name on the back of the test, and read the instructions below.) Good Luck! This midterm consists of 5 questions on 11 pages (including this one). When you receive the signal to start, please make sure that your copy is complete. Comments are not required except where indicated, although they may help us mark your answers. They may also get you part marks if you can t figure out how to write the code. If you use any space for rough work, indicate clearly what you want marked. Total Pages = 11 Page 1 cont d...

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3 Question 1. [6 marks] Complete the following functions according to their docstring descriptions. Requirements: To avoid duplicate code, your better rate function must call mortgage cost. Given the initial size of a mortgage, p, and an interest rate, r, the formula for the cost of the mortgage after n years is a: Part (a) [3 marks] def mortgage_cost(n, p, r): (int, int, float) -> int Return the cost of a mortgage after n years with an initial size of p and interest rate r. Use the formula given in Equation (1) above. a = p(1 + r) n (1) Part (b) [3 marks] def better_rate(p, r1, n1, r2, n2): (int, float, int, float, int) -> str Return the cheaper of the two mortgage options as a str. Given an initial mortgage size p, one mortgage option with interest rate r1 and number of years n1 and a second mortgage option with interest rate r2 and number of years n2, determine the cheaper total mortgage cost and return the str, Mortgage option with interest rate r for n years is cheaper." where r and n are one of r1 and n1 or r2 and n2 respectively. Student #: Page 3 of 11 cont d...

4 Question 2. [5 marks] Suppose these functions have been defined: def f(a, b, c): return (a > b and c < a) def g(a, b, c): if f(a, b, c): return a elif f(b, a, c): return b else: return c The following program runs without errors. Fill in the boxes below to show the output printed. if name == main : x = 10 y = 8 z = 6 print(f(x, y, z)) output: print(f(y, y, y)) output: print(g(z, y, x)) output: z = g(y, x, z) print(g(x, z, y)) output: a = 9 print(a < g(z, y, x)) output: Student #: Page 4 of 11 cont d...

5 Question 3. [6 marks] The wind chill level is rated according to ranges of temperatures in celsius less than or equal to 0, categorized as follows: Wind Chill Range Celsius values Warning Low 0 to -9 Moderate -10 to -24 Cold -25 to -44 danger of frostbite Extreme -45 or colder skin may freeze in minutes Write a program that uses input to prompt the user for a wind chill temperature value and then prints a message about the category and warning associated with the value. This program consists of two parts: a function named windchill category on this page and a main block on the next page. Your program should ask the user for input using the string Please enter the wind chill value:. It should then print one of the two messages below (whichever one is appropriate, based on the values entered by the user): The wind chill value belongs to category X with no special warnings., where X is replaced with Low or Moderate. The wind chill value belongs to category Y with the warning Z, where Y is replaced with Cold or Extreme and Z is replaced by danger of frostbite or skin may freeze in minutes. def windchill_category(wc): (int) -> str Return the category that wind chill value wc (an int less than or equal to 0), belongs to. The category is one of Low, Moderate, Cold or Extreme. >>> windchill_category(-7) Low >>> windchill_category(-15) Moderate >>> windchill_category(-50) Extreme Student #: Page 5 of 11 cont d...

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7 More space for your answer to Question 3. if name == main : Student #: Page 7 of 11 cont d...

8 Question 4. [7 marks] Complete the following functions according to their docstring descriptions. Part (a) [2 marks] def compress(s): (str) -> str Return a new str the same as str s, but with all white space removed. For example Way up on top. would return Wayupontop. Requirement: Do not use str method replace(). Part (b) [3 marks] def reverse(s): (str) -> str Return a new str the same as str s, but reversed. Part (c) [2 marks] def create_palindrome(s): (str) -> str Return a new str from str s, that is s followed by the reverse of s. For example, create_palindrome( hello ) would return helloolleh. Student #: Page 8 of 11 cont d...

9 Question 5. [6 marks] Complete the functions according to their docstring descriptions. Part (a) [3 marks] def square_elements(l): (list) -> list Return a new list in which each element is the corresponding element of list L squared. The elements of list L are all numeric. Part (b) [3 marks] def contains_substring(l,s): (list of str, str) -> bool Return True if any element in the list of strs L contains the substring s, and False otherwise. Student #: Page 9 of 11 cont d...

10 [Use the space below for rough work. This page will not be marked, unless you clearly indicate the part of your work that you want us to mark.] Student #: Page 10 of 11 cont d...

11 Short Python function/method descriptions: builtins : len(object) -> integer Return the number of items of a sequence or mapping. abs(number) -> number Return the absolute value of the given number. max(a, b, c,...) -> value With two or more arguments, return the largest argument. min(a, b, c,...) -> value With two or more arguments, return the smallest argument. raw_input([prompt]) -> string Read a string from standard input. The trailing newline is stripped. The prompt string, if given, is printed without a trailing newline before reading. int: int(x) -> integer Convert a string or number to an integer, if possible. A floating point argument will be truncated towards zero. str: S.count(sub[, start[, end]]) -> int Return the number of non-overlapping occurrences of substring sub in string S[start:end]. S.find(sub [,start [,end]]) -> int Return the lowest index in S where substring sub is found, such that sub is contained within s[start,end]. Return -1 on failure. S.isdigit() -> bool Return True if all characters in S are digits and len(s) >=1, False otherwise. S.islower()/isupper() -> bool Return True if all cased characters in S are lowercase/uppercase and there is at least one cased character in S, False otherwise. If sep is not specified, any whitespace string is a separator. S.replace (old, new[, count]) -> string Return a copy of string S with all occurrences of substring old replaced by new. If the optional argument count is given, only the first count occurrences are replaced. S.startswith(prefix[, start[, end]]) -> bool Return True if S starts with the specified prefix, False otherwise. With optional start, test S beginning at that position. With optional end, stop comparing S at that position. S.strip([chars]) -> string or unicode Return a copy of the string S with leading and trailing whitespace removed. If chars is given, remove characters in chars instead. Last Name: First Name: Page 11 of 11 End of Examination