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.
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 2 - corrected multiple errors in Question 3 and its marking code. (this question was not marked).
Write a function named divisibleby(x,n) that takes a list argument named x and an integer argument n. Your function should return a (new) list consisting of all the values of x which are divisible by n. For example, if x=[0, 3, 4, 9] then divisibleby(x,3) should return [0, 3, 9].
def divisibleby(x,n):
return [i for i in x if i%n == 0]
x=[0, 3, 4, 9]
divisibleby(x,3)
Write a function named mergedicts that takes one list argument named l. The list l contains dictionaries. Your function should return one list containing all key:value pairs in all dictionaries in l. For example if l = [{ 'a': 3, 'b': 9}, {1:2, "x":'y'}, {'sum':32}] then mergedicts(l) should return { 'a': 3, 'b': 9, 1:2, "x":'y', 'sum':32}. You may assume there are no duplicate keys.
def mergedicts(l):
return {k:d[k] for d in l for k in d}
l = [{ 'a': 3, 'b': 9}, {1:2, "x":'y'}, {'sum':32}]
mergedicts(l)
Write a recursive function named rtest that takes a string argument named s and function argument f. Your function should call f with successive characters of s until the return value is zero or all values of s have been tested. Your function does not return a value. For example if x='abc' and f('b') returns 0 then rtest would call f('a') and f('b') and then return. It would not call f('c').
def rtest(s,f):
if not s or f(s[0]) == 0:
return
else:
rtest(s[1:],f)
def f(c):
print(c)
return 0 if c == 'b' else 1
rtest("abc",f)
Set the variable pat to a regular expression that matches a part number string created according to the following sequence:
For example, re.search(pat,'XT00M99V-v2') would return a match object but re.search(pat,'XT000M12G-v2') would not.
pat=r'^XT00?M?[0-9]{2,3}(G|V)(-v2)?$'
import re
re.search(pat,'XT00M99V-v2'),re.search(pat,'XT000M12G-v2')
# exam validation code; do not modify
def examcheck():
import copy, hashlib, re
from random import randint, choices, shuffle
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():
import random
n=random.randint(3,5)
x1=random.sample(range(0,100,n),k=random.randint(2,4))
x2=random.sample(range(0,100,n),k=random.randint(2,4))
x2=[i+random.randint(1,n-1) for i in x2]
x=x1+x2
random.shuffle(x)
x.sort()
x1.sort()
y=divisibleby(x,n)
assert y == x1, f'divisible{x,n} returns {y} instead of {x1}'
def q2():
ll=[randint(2,4) for i in range(randint(2,4))]
n=sum(ll)
r=randwords(n)+list(range(n))
shuffle(r)
l=[{r.pop():r.pop() for i in range(n)} for n in ll]
l0=copy.deepcopy(l)
y=mergedicts(l)
assert len(y) == n and all([k in y and y[k] == d[k] for d in l0 for k in d]), \
"mergedicts({}) returns {}".format(l0,y)
def q3():
import random
checkrecursive(rtest)
n=random.randint(3,5)
s=''.join([chr(random.randint(ord('a'),ord('f')))
for i in range(random.randint(3,7))])
sl=[]
c=s[random.randint(0,len(s)-1)]
def found(x):
sl.append(x)
return 0 if x == c else 1
s0=copy.deepcopy(s)
rtest(s,found)
assert sl == list(s0[:s0.index(c)+1]), \
f'rtest("{s}"",f) called f with {sl}'+ \
f' when f("{c}") returns 0'
def q4():
ok=["XT00M123G-v2", "XT0M123G-v2", "XT00123G-v2",
"XT00M12G-v2", "XT00M123V-v2","XT00M123G"]
nok=["X00M123G-v2", "XT000M123G-v2", "XT00m123G-v2",
"XT00M1234G-v2", "XT00M123X-v2", "XT00M123G0"]
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()