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 no errors were found in your answer to question N.
Comment out any code that causes errors and re-run Cell ► Run All
before submitting your notebook.
When the exam time is over, save the notebook (the .ipynb file) and upload it to the appropriate dropbox on the course web site.
Version 3 (corrected marking of Questions 1 and 3 and example in Question 4).
Write a function named dictsel that takes an argument named d that is a dictionary. The keys of d are strings and the values are integers with values 0 or 1. Your function should return a list containing the keys of each element for which the value is non-zero. For example, if d={ 'ab': 0, 'def': 1, 'x': 1, 'ABC': 0} then dictsel(d) should return a list containing ['def', 'x'].
def dictsel(d):
return [k for k in d if d[k]]
d={ 'ab': 0, 'def': 1, 'x': 1, 'ABC': 0}
dictsel(d)
Write a function named t2d that takes a list of tuples named l. Your function should create a dictionary by using the first element of each tuple as the key and the value should be a tuple containing the rest of the values. For example if l = [ ('add', 1), ('sub', 2, 32, 16), ('jmp',3,64)] then t2d(l) should return the dictionary {'add': (1,), 'sub': (2, 32, 16), 'jmp': (3, 64)}.
def t2d(l):
return {t[0]:tuple(t[1:]) for t in l}
l = [ ('add', 1), ('sub', 2, 32, 16), ('jmp',3,64)]
t2d(l)
Write a recursive function named pairup that takes two list arguments named l1 and l2. The function should return a list of tuples where each tuple contains one element from each of the two arguments. For example if l1=[0, 1, 2] and l2=['a', 'b', 'c'] then pairup(l1,l2) would return [(0,'a'), (1,'b'), (2,'c')]. You can assume l1 and l2 are the same length.
def pairup(l1,l2):
if not l1:
return []
else:
return [(l1[0],l2[0])]+pairup(l1[1:],l2[1:])
# solution that modifies l1, l2
def pairup(l1,l2):
if not l1:
return []
else:
t = l1.pop(), l2.pop()
return pairup(l1,l2)+[t]
l1=[0, 1, 2]
l2=['a', 'b', 'c']
print(pairup(l1,l2))
print(l1,l2)
Set the variable pat to a regular expression that matches a part number string created according to the following sequence:
ELJ-F1UH123M
For example, re.search(pat,'ELJ-F1UH123M') would return a match object but re.search(pat,'ELM-F1UH123M') would not.
pat=r'^EL[JKL]-F?\dUH\d{3}M$'
import re
print(re.search(pat,'ELJ-F1UH123M'))
print(re.search(pat,'ELM-F1UH123M'))
# exam validation code; do not modify
def examcheck():
import copy, hashlib, re
from random import randint, choices, shuffle, sample
def randwords(n):
l = set()
while len(l)<n:
l |= set((''.join([chr(randint(97,122)) for i in range(randint(2,5))]),))
return list(l)
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):
# 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):
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():
n=randint(4,6)
d=dict(zip(randwords(n),[randint(0,1) for i in range(n)]))
d0=copy.deepcopy(d)
l=dictsel(d)
assert len(l) == sum(d0.values()) and \
all((k in l for k,v in d0.items() if v) ) and \
all((k not in l for k,v in d0.items() if not v) ), \
"dictsel({}) returns {}".format(d0,l)
def q2():
n=randint(5,9)
l=[tuple(randwords(1)+[randint(1,9) for i in range(randint(2,4))]) \
for j in range(n)]
l0=copy.copy(l)
d=t2d(l)
assert len(d) == n and \
all([k in [t[0] for t in l0] for k in d]) and \
all([t[1:] == d[t[0]] for t in l0]), \
"l2d({}) returns {}".format(l0,d)
def q3():
checkrecursive(pairup)
n=randint(3,5)
l1=randwords(n)
l2=[randint(1,9) for _ in range(n)]
l10,l20=copy.copy(l1),copy.copy(l2)
l=pairup(l1,l2)
assert l == [t for t in zip(l10,l20)],"pairup({},{}) returns {}".format(l1,l2,l)
def q4():
ok=['ELJ-F1UH123M', 'ELL-F1UH123M', 'ELJ-1UH123M',
'ELJ-F9UH123M', 'ELJ-F1UH999M' ]
nok=[' ELJ-F1UH123M', 'ELM-F1UH123M','ELJF1UH123M',
'ELJ-F.U123M', 'ELJ-F1UH12M', 'ELJ-F1UH123' ]
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()