Due: 02 November by 11:00 pm

Weight: This assignment is worth 4% of your final grade.

Purpose, Skills, & Knowledge: The purposes of this assignment are:

• To practice the same problem-solving skills we’ve learning thus far, but in Python.
• To practice running Python scripts from R.

Assessment: Each question indicates the % of the assignment grade, summing to 100%. The credit for each question will be assigned as follows:

• 0% for not attempting a response.
• 50% for attempting the question but with major errors.
• 75% for attempting the question but with minor errors.
• 100% for correctly answering the question.

Rules:

• Problems marked SOLO may not be worked on with other classmates, though you may consult instructors for help.
• For problems marked COLLABORATIVE, you may work in groups of up to 3 students who are in this course this semester. You may not split up the work – everyone must work on every problem. And you may not simply copy any code but rather truly work together.
• Even though you work collaboratively, you still must submit your own solutions.

### 1) Staying organized [SOLO, 5%]

Download and use this template for your assignment. Inside the “hw8” folder, open and edit the R script called “hw8.py” and fill out your name, GW Net ID, and the names of anyone you worked with on this assignment.

### Writing test functions

For each of the following functions, write a test function first, and then write the function. Your test functions will count for half of the available credit for each problem. Think carefully about the test cases to include in your test functions.

### 2) kthDigit(x, k) [SOLO, 15%]

Given two integers, x and k, return the kth digit of x, counting from the right. So:

• kthDigit(789, 1) returns 9
• kthDigit(789, 2) returns 8
• kthDigit(789, 3) returns 7
• kthDigit(789, 4) returns 0

Negative numbers should work, too, so kthDigit(-789, 1) returns 9.

### 3) isEvenPositiveInt(x) [SOLO, 15%]

Given an arbitrary value x, return True if it is an integer, and it is positive, and it is even (all 3 must be true), or False otherwise. If the value x is not an integer, the function should return False rather than error. So, isEvenPositiveInt("yikes!") returns False, and isEvenPositiveInt(123456) returns True.

### 4) getTheCents(n) [SOLO, 15%]

Write the function getTheCents(n) which takes a value n that represents a payment in US dollars and returns the number of cents in the payment. For example, if n is 2.45, the function should return 45. If n is an integer, the function should return 0, as it has 0 cents; if it isn’t a number, it should return None, because a non-number payment make no cents (ha!). If the payment has partial cents (for example, 3.953), it should be rounded to the nearest cent (in this case, 95 cents).

#### 5) isPrime(n) [COLLABORATIVE, 15%]

Write the function isPrime(n) which takes a non-negative integer, n, and returns True if it is a prime number and False otherwise.

### 6) numDigits(n) [SOLO, 15%]

Write the function numDigits(n) that takes a possibly-negative integer and returns the number of digits in it. So, numDigits(12345) returns 5, numDigits(0) returns 1, and numDigits(-111) returns 3. One way you could solve this is to convert n to a string and use str_length(), but you cannot do that since you may not use strings here.

### 7) reverseString(s) [COLLABORATIVE, 15%]

Write a function that returns the string in reverse order. So if s equals "abcde", reverseString(s) should equal "edcba". You may assume that s only contains upper and/or lower case letters, but your solution must correctly return capital letters in their appropriate order. For example, reverseString("aWordWithCaps") should return "spaChtiWdroWa".

### 8) Submit your files [SOLO, 5%]

Create a zip file of all the files in your R project folder for this assignment and submit the zip file on Blackboard.

EMSE 4574: Programming for Analytics (Fall 2020) |
Tuesdays | 12:45 - 3:15 PM | Dr. John Paul Helveston | jph@gwu.edu
Content 2020 John Paul Helveston. See the licensing page for details.