[SOLVED] python PROGRAMMING FOR SCIENTISTS COMP1730/6730

PROGRAMMING FOR SCIENTISTS COMP1730/6730
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Read all instructions carefully!
The exam consist of questions of different kinds: Some require you to write an explanation (free text answer), some are multiple choice, and some require you to write and upload a piece of python code. The questions are not equally weighted. The maximum marks for each question is specified in brackets next to the question. Questions are not ordered by difficulty: you should read through all the questions first, then decide the order in which you attempt them.
For free text and multiple-choice questions, you should enter your answers directly in the text fields below (or answer by selecting from the choices for the multiple-choice questions). Your answers are saved automatically.
There is no (known) limit to the length of answers, but you should try to keep your answers short and clear. Answers that contain correct statements may gain less than full marks if they also contain irrelevant or incorrect statements.
For the programming problems, you should write your solutions into the python files provided, and test them using the testing programs that are also provided. When you have completed your solution to one of the problems, you must upload your solution file into the exam (using the file selection button for each programming problem, or by drag-and-drop).
Solutions to programming problems will be marked on the basis of functionality only. To be fully functional means solving the problem that is described in the question. The tests implemented in the testing programs are designed to help you understand the problem and debug your solution. Passing the tests does not prove that your solution is correct. Failing the tests proves that your solution is wrong. A partially functional solution may receive some marks. However, marks are not proportional to the number of tests passed. A submission that does not run (for example, due to syntax errors), that violates the format instructions, or that fails every test case will receive zero marks.
The exam has an extra question for students taking COMP6730 (the masters course) only. This question is clearly labelled COMP6730 only. Students in COMP1730 (undergraduate) will not receive any marks for answering this question. For students in the masters course, the exam mark will be rescaled from a mark out of 24 to a mark out of 20.
The lab exam environment is exactly the same as the regular CSIT lab computer environment except that internet access is limited to the course web site (cs.anu.edu.au/courses/comp1730) only and that you will not be able to see your normal home directory. In particular, you should find the same python IDEs (Spyder, PyCharm, IDLE, etc) in the exam environment as you have in the labs.
If the environment is unfamiliar, you may want to quickly review the first part of Lab 1.
Question 1 [3 Marks]
Below are three suggested function names. For each name, answer (a) whether this is a valid name in python, and (b) describe in what situation, if any, it would be appropriate to use as a function name.
1 i)

over-21
1 ii)
_2_steps_forward
1 iii)
Def
Question 2 [1 Marks]
For each of the following statements, answer whether it is true or false. (There is no mark penalty for incorrect answers, but your answer must be correct for more than half the statements to receive any marks. You can unanswer a question by clicking the Clear button next to it.)
The arguments provided in a function call map to the functions parameters in the same order (i.e., first argument to first parameter, and so on).
A function must be defined before it can be called. A function can only be called from one place within a program.
A function suite can contain only one return statement.
The name of a function can not be used as a variable name anywhere in the file where the function is defined.
Clear Clear Clear Clear Clear
True False
Question 3 [3 Marks]
Below are three attempts to define a function equal_ratio(a, b, c, d). The arguments should all be integers, and the

function should return True if and only if the ratios a/b and c/d are equal. For example, equal_ratio(1,2,2,4) should return True, because 1/2 == 2/4. b and d must be different from zero, as otherwise the ratio is undefined.
For each of the functions below, answer whether it is correct or not. Correct mean that the function runs without error and returns the right answer for all valid arguments (that is, a, b, c and d are all integers and b and d are not zero). If a function is not correct, explain precisely what is wrong with it. For example, if it has a syntax error, you should describe which part of which line is wrong; if the function runs but returns the wrong answer, give a concrete example of arguments that cause this to happen and explain why it does. Writing a new function without explaining what is wrong with the given function is not an acceptable answer to the question (regardless of whether that function is correct or not).
3 i)
def equal_ratio(a, b, c, d): return a // c == b // d
3 ii)
def equal_ratio(a, b, c, d):
a * d == c * b or a == c and b == d
3 iii)
def equal_ratio(a, b, c, d):
return print(a / b) == print(c / d)
Question 4 [1 Marks]
A function is defined as follows:
def funA(x): y=2*x-1
return y
z = x ** 2 return z

Give an example of an argument that will make the function return the value 16 of type int, or explain why this can not happen.
Question 5 [4 Marks]
Here is a definition of a somewhat complicated and poorly documented function:
def funB(x): x must
i=0
y = x[0] a=0 while i <j=0 z=0 whilej=j+1 if z > a:
y = x[i] a = max(z, a)
i=i+1 return y
5 i) [2 Marks]
Explain what funB does in general. Write your explanation so that it is like a good docstring for the function. In other words, a good explanation should describe the purpose of the function, not step-by-step how it works.
5 ii) [2 Marks]
The author of the function above has made it clear that it is intended to work only on arguments that are sequences. But does it work on any sequence? Write down all requirements on the argument sequence that are necessary for the function to run without causing a runtime error.
be a sequence
len(x):
j < len(x):if x[i] == x[j]: z=z+1Question 6 [4 Marks]An integer n is called a square if n = m * m for some integer m. As we all know, 1, 4, 9, 16, and 25 are squares. But what about bigger numbers, like 543168? (It’s not a square. 543169 is.) Write a function, is_square that takes as argument a positive integer and return True if that integer is the square of another integer, and False if it is not.A skeleton file called is_square.py is provided (it is on the desktop). A testing program called test_is_square.py is also provided. The testing program will test the function is_square in the file is_square.py.The function that you write must be named is_square and it must have one parameter.You can assume that the argument is a positive integer.The function must return True or False.Remember that your solution must contain only function definitions and comments (optionally, import statements). If it contains anything else, it is invalid and you will receive zero marks. Running the testing program will tell you if your file is invalid.Hint: The square root function returns a floating point number. Even for integers of a relatively modest size, such as 1016, the difference between a perfect square and the same number plus or minus one disappears when we take the square root. The square root function can be useful, but you need to think about how to work around the limited precision.Important: You must upload your solution into the exam, by drag-and-dropping it into the space below. After upload, you will see the contents of the file you uploaded below. You cannot edit the text below, but if you want to make changes, edit your solution file and drop it in or upload it again.Drop here or click to upload your code Browse… No file selected.Clear codeQuestion 7 [4 Marks]A sequence of numbers is called super-increasing if and only if every number in the sequence is strictly greater than the sum of all numbers preceding it in the sequence. The first element in the sequence can be any number.For example, the sequences 1,3,5,11,21 and -2,1,2 are both super-increasing; the sequence 1,3,5,7,19 is increasing, but not super-increasing.Write a function super_increasing(seq) that takes as argument a sequence of numbers and returns True if the sequence is super-increasing and False if it is not.A skeleton file called super_increasing.py is provided (it is on the desktop). A testing program called test_super_increasing.py is also provided. The testing program will test the function super_increasing in the file super_increasing.py.The function that you write must be named super_increasing and it must have one parameter.You can assume that the argument is a non-empty sequence of numbers.You should not assume that values in the sequence are unique or increasing.You should not make any assumption about the type of the argument other than that it is a sequence type; likewise, you should not make any assumption about the type of the numbers in the sequence, other than that they are numbers. The function must not modify the argument sequence.The function must return a value of type bool.Remember that your solution must contain only function definitions and comments. If it contains anything else, it isinvalid and you will receive zero marks. Running the testing program will tell you if your file is invalid.Important: You must upload your solution into the exam, by drag-and-dropping it into the space below. After upload, you will see the contents of the file you uploaded below. You cannot edit the text below, but if you want to make changes, edit your solution file and drop it in or upload it again.Drop here or click to upload your code Browse… No file selected.Clear codeQuestion 8 [4 Marks] COMP6730 students onlyThe following function computes the largest absolute difference between any pair of values in a list of numbers:def mpd(x):”’Returns the largest pair-wise difference in x.”’i = 1 # i is the distance between elements in the pair a = -1 # a keeps track of the maximumwhile i < len(x):y=i+1while y < len(x):# check the pair in both directions to find the largest absolute difference: if x[y] – x[y – i] > a:
a = x[y] x[y i] if x[y i] x[y] > a: a = x[y i] x[y]
y = y + 1 # increment loop variable to make sure the loop ends i=i+1
# return the largest difference found: return a
Describe all the ways in which the function above can be improved. To gain marks, your suggested improvements must be specific. (For example, if you think the function should have additional comments, describe what comments should be added and where. Just answering more comments is not enough.)