Answer all four (4) questions.
You have 110 minutes to complete the exam.
This is an open-book exam. All written material is allowed.
No electronic devices other than a flash drive and the lab PC may be used during the exam.
No communication with others (electronic, verbal, written or otherwise) is allowed during the exam. Violations will result in a mark of zero and disciplinary action.
Add the Python code described below in the cells provided.
Test your code using the menu item Cell ► Run All
The message "Solution to question N may be correct." at the bottom of the notebook means that your answer to question N may be correct.
When the exam time is over, save the notebook (the .ipynb file) and upload it to the appropriate dropbox on the course web site.
This question tests your ability to iterate through a data structure while testing, creating and/or modifying objects.
Write a function named addkey that takes one argument named x. The argument is a dictionary where the keys are integers and the values are strings. Modify the dictionary x
so that the key is appended to the value. For example, if x is { 3: 'x', 7: 'Page ', 4: '' } the result should be { 3: 'x3', 7: 'Page 7', 4: '4' }. Your function should return the modified dictionary.
def addkey(x):
for k in x:
x[k]=x[k]+str(k)
return x
This question tests your ability to work with compound (nested) data structures.
Write a function named elemadd that takes one list argument named x. x is a list whose elements are n-element lists. Your function should return a list containing the sum of the corresponding elements of the lists in x. For example if x is [[1,2], [3,-1], [7,8]] then elemadd(x) should return [11,9]. Your solution may only use the functions len, range and enumerate.
def elemadd(x):
m=len(x[0])
s=[0]*m
for t in x:
for i in range(m):
s[i] += t[i]
return s
This question tests your ability to write a recursive function.
Write a recursive function named oddcall that takes a list argument named l and a function argument named f. f takes one argument. Your function should call the function f with each value in the argument list x that is odd (it's the value that should be odd, not the index). For example oddcall([1,2,3,4],print) would print lines with 1 and 3.
def oddcall(l,f):
if not l:
return
else:
if l[0] % 2:
f(l[0])
oddcall(l[1:],f)
This question tests your ability to write a regular expression.
Set the variable pat to a regular expression that matches part numbers created according to the following sequence:
pat=r'^ATF?\d\d\d?[BQZ]*-\d\d?'
# exam validation code; do not modify
def examcheck():
def checksorted(l):
assert all((l[i] <= l[i+1] for i in range(len(l)-1))), \
"result is not sorted: {}".format(l)
def checkfunctions(f,l):
u=[s for s in f.__code__.co_names if s not in l]
assert not u, "You used the function(s): {}".format(u)
def checkrecursive(f):
s=f.__name__
assert s in f.__code__.co_names, "{} is not recursive".format(s)
def checkhash(l,n):
import hashlib
# print(hashlib.md5(''.join(l).encode('utf8')).hexdigest())
assert hashlib.md5(''.join(l).encode('utf8')).hexdigest() == n, \
'wrong values in list: {} ... {}'.format(l[0],l[-1])
def checkre(pat,ok,nok):
import re
for s in ok:
assert re.search(pat,s), \
"pattern '{}' didn't match string '{}'".format(pat,s)
for s in nok:
assert not re.search(pat,s), \
"pattern '{}' matched string '{}'".format(pat,s)
def q1():
from random import randint, shuffle
import copy
n=list(range(randint(3,6)))
shuffle(n)
x={k:chr(randint(97,122))*randint(1,3) for k in n}
x0=copy.deepcopy(x)
y=addkey(x)
assert len(y) == len(x)
assert all(int(y[k][-1]) == k for k in y)
assert all(y[k][:-1] == x0[k] for k in y)
def q2():
from random import randint
checkfunctions(elemadd,['len', 'range', 'enumerate'])
m=randint(2,4)
x=[list(randint(0,9) for i in range(m)) for j in range((randint(2,4)))]
s=[sum(t) for t in zip(*x)]
y=elemadd(x)
assert len(y) == m
assert y == s
def q3():
from random import randint
checkrecursive(oddcall)
l=[randint(0,9) for i in range(randint(4,9))]
fl=[]
found=lambda x:fl.append(x)
oddcall(l,found)
cl=list(filter(lambda x:x%2,l))
assert fl == cl, "oddcall({}) calls f with: {}, not {}".format(l,fl,cl)
def q4():
ok=['AT00-0', 'ATF999BQZ-99', 'ATF999BQZ-12', 'ATF999BQZ-99', 'ATF999BQZ-34' ]
nok=[' AT00-0', 'ATFF999BQZ-123', 'ATF9BQZ-99', 'ATF999BQZ33', 'ATF9999ZB-99' ]
checkre(pat,ok,nok)
for i,s in ((i,'q%d'%i) for i in range(1,20)):
if s in locals():
try:
locals()[s]()
print("Solution to question {} may be correct.".format(i))
except Exception as e:
print("Failed check for question {}: {}".format(i,e))
examcheck()