CptS – Assignment 3 Solution

Description

Problems:

1. (Dictionaries)

   1. getNumCases(data,counties,months) – 10%

Assume that you work for a “Healthcare Data Analytics” company and you write scripts to process various dataset. In your analysis, you use the CDC’s COVID-19 dataset. For example, the following dataset reports the monthly new COVID cases for some counties in WA.

CDCdata =

{‘King’:{‘Mar’:2706,‘Apr’:3620,‘May’:1860,‘Jun’:2157,‘July’:5014,‘Aug’:4327,‘Sep’:2843},

‘Pierce’:{‘Mar’:460,‘Apr’:965,‘May’:522,‘Jun’:647,‘July’:2470,‘Aug’:1776,‘Sep’:1266},

‘Snohomish’:{‘Mar’:1301,‘Apr’:1145,‘May’:532,‘Jun’:568,‘July’:1540,‘Aug’:1134,‘Sep’:811},

‘Spokane’:{‘Mar’:147,‘Apr’:222,‘May’:233,‘Jun’:794,‘July’:2412,‘Aug’:1530,‘Sep’:1751},

‘Whitman’ : {‘Apr’:7,‘May’:5,‘Jun’:19,‘July’:51,‘Aug’:514,‘Sep’:732, ‘Oct’:278} }

The keys of the dictionary are the county names, and the values are the dictionaries which include the monthly new COVID cases. Note that some counties may not have any new cases in some months.

Define a function, getNumCases, which calculates the total number of new cases for a given list of counties during a given list of months. For example:

getNumCases(CDCdata,[‘Whitman’],[‘Apr’,‘May’,‘Jun’]) returns 31, and

getNumCases(CDCdata,[‘King’,‘Pierce’],[‘July’,‘Aug’]) returns 13587.

(Important note: Your function should not hardcode the county names and the month abbreviations. It should simply iterate over the keys that appear in the given dictionary. You will be deducted points if you hardcode any keys. )

You can start with the following code:

def getNumCases(data,counties,months):

#write your code here

2. getMonthlyCases(data) – 15%

Assume, your supervisor asks you to reformat the data and create a dictionary that includes the number of cases for each county, organized by months. For example, when you reformat the above dictionary you will get the following.

{‘Mar’:{‘King’:2706,‘Pierce’:460,‘Snohomish’:1301,‘Spokane’:147},

‘Apr’:{‘King’:3620,‘Pierce’:965,‘Snohomish’:1145,‘Spokane’:222,‘Whitman’:7},

‘May’:{‘King’:1860,‘Pierce’:522,‘Snohomish’:532,‘Spokane’:233,‘Whitman’:5},

‘Jun’:{‘King’:2157,‘Pierce’:647,‘Snohomish’:568,‘Spokane’:794,‘Whitman’:19},

‘July’:{‘King’:5014,‘Pierce’:2470,‘Snohomish’:1540,‘Spokane’:2412,‘Whitman’:51},

‘Aug’:{‘King’:4327,‘Pierce’:1776,‘Snohomish’:1134,‘Spokane’:1530,‘Whitman’:514},

‘Sep’:{‘King’:2843,‘Pierce’:1266,‘Snohomish’:811,‘Spokane’:1751,‘Whitman’:732},

‘Oct’:{‘Whitman’:278}}

3. mostCases(data) – 15%

Assume, you would like to find the month that had the maximum total number of new cases in all counties. For example:

mostCases(CDCdata) returns (‘July’, 11487)

#i.e., July has the max number of total new cases, which is 11487.

Your function definition should not use loops or recursion but use the Python map and reduce

functions. You should also use the getMonthlyCases function you defined in part(b). You may define and call helper (or anonymous) functions, however your helper functions should not use loops or recursion.

2. (Dictionaries and Lists)

1. searchDicts(L,k)– 5%

Write a function searchDicts that takes a list of dictionaries L and a key k as input and checks each dictionary in L starting from the end of the list. If k appears in a dictionary, searchDicts returns the value for key k. If k appears in more than one dictionary, it will return the one that it finds first (closer to the end of the list).

For example:

L1 = [{“x”:1,“y”:True,“z”:“found”},{“x”:2},{“y”:False}]

searchDicts(L1,“x”) returns 2 searchDicts(L1,“y”) returns False searchDicts(L1,“z”) returns “found” searchDicts(L1,“t”) returns None

You can start with the following code: def searchDicts(L,k):

#write your code here

2. searchDicts2(tL,k) – 10%

Write a function searchDicts2 that takes a list of tuples (tL) and a key k as input. Each tuple in the input list includes an integer index value and a dictionary. The index in each tuple represent a link to another tuple in the list (e.g. index 3 refers to the 4^th tuple, i.e., the tuple at index 3 in the list) searchDicts2 checks the dictionary in each tuple in tL starting from the end of the list and following the indexes specified in the tuples.

For example, assume the following:

[(0,d0),(0,d1),(0,d2),(1,d3),(2,d4),(3,d5),(5,d6)]

0 1 2 3 4 5 6

The searchDicts2 function will check the dictionaries d6,d5,d3,d1,d0 in order (it will skip over d4 and d2) The tuple in the beginning of the list will always have index 0.

It will return the first value found for key k. If k is couldn’t be found in any dictionary, then it will return None.

For example:

L2 = [(0,{“x”:0,“y”:True,“z”:“zero”}),

(0,{“x”:1}),

(1,{“y”:False}),

(1,{“x”:3, “z”:“three”}),

(2,{})]

searchDicts2 (L2,“x”) returns 1

searchDicts2 (L2,“y”) returns False

searchDicts2 (L2,“z”) returns “zero”

searchDicts2 (L2,“t”) returns None

(Note: I suggest you to provide a recursive solution to this problem.

Hint: Define a helper function with an additional parameter that hold the list index which will be

searched in the next recursive call.)

You can start with the following code:

def searchDicts2(L,k):

#write your code here

3. adduptoZero(L,n) – 10%

Write a function, adduptoZero, which takes a integer list (L) and a number (n) as argument, and it returns the L’s sublists of length “n”, where the elements in each sublist adds up to “0”.

For example:

adduptoZero([1,-2,3,-4,-5,6,-7,8,9,-10], 3) returns

[[-4, –5, 9], [-2, –7, 9], [-2, –4, 6], [1, 3, –4], [1, 6, –7], [1, 9, –10]] adduptoZero(list(range (-3,3), 4) returns [[-3, 0, 1, 2], [-2, –1, 1, 2]] adduptoZero(list(range (1,10)),2) returns []

3. • You can assume that the input list (L) does not have any duplicates.

3. • You can use the “combinations” function from itertools to get the possible combinations of length “n”. “combinations” returns a collection of tuples and you need convert this output to a list of tuples.

3. • Make sure to import itertools in your HW3.py file, i.e., from itertools import combinations

You can start with the following code:

def adduptoZero(L,n):

#write your code here

4. getLongest(L) – 10%

Write a function, getLongest, which takes an arbitrarily nested list of strings (L) and it returns the longest string in L. Note that the longest string can be found at any nesting level, so your function should recursively check all sublists. You should not assume a max depth for the nesting. If there are more than one string that have the max length, you should return the one that appears earlier in the list.

For example:

getLongest([‘1’,[’22’,[‘333’,[‘4444’,‘55555’,[‘666666’]],‘7777777’],‘4444’],’22’]) returns ‘7777777’

getLongest([[‘cat’,[‘dog’,‘horse’],[‘bird’,[‘bunny’,‘fish’]]]])

returns ‘horse’

You can start with the following code:

def getLongest (L):

#write your code here

5. Iterators apply2nextN()– 20%

Create an iterator that represents the aggregated sequence of values from an input iterator. The iterator will be initialized with a combining function (op), an integer value (n) , and an input iterator (input). When the iterator’s __next__() method is called, it will combine the next “n” values in the “input“ by applying the “op” function and it will return the combined value. The iterator should stop when it reaches the end of the input sequence. If the input sequence is infinite, the apply2nextN will return an infinite sequence as well.

For example:

iSequence = apply2nextN(lambda a,b:a+b, 3, iter(range(1,32)))

# iSequence represents the sequence [6, 15, 24, 33, 42, 51, 60, 69, 78, 87, 31]

Testing your functions (5%)

We will be using the unittest Python testing framework in this assignment. See https://docs.python.org/3/library/unittest.html for additional documentation.

The file HW3SampleTests.py provides some sample test cases comparing the actual output with the expected (correct) output for some problems. This file imports the HW3 module (HW3.py file) which will include your implementations of the given problems.

Rename the HW3SampleTests.py file as HW3Tests.py and add your own test cases in this file. You are expected to add at least 2 more test cases for each problem. Make sure that your test inputs cover all boundary cases. Choose test input different than those provided in the assignment prompt.

In Python unittest framework, each test function has a “test_” prefix. To run all tests, execute the following command on the command line.

python -m unittest HW3SampleTests

You can run tests with more detail (higher verbosity) by passing in the -v flag:

python -m unittest -v HW3SampleTests

If you don’t add new test cases you will be deduced at least 5% in this homework.

Main Program

In this assignment, we simply write some unit tests to verify and validate the functions. If you would like to execute the code, you need to write the code for the “main” program. Unlike in C or Java, this is not done by writing a function with a special name. Instead the following idiom is used. This code is to be written at the left margin of your input file (or at the same level as the def lines if you’ve indented those.

if __name__ == ‘__main__’:

…code to do whatever you want done…