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.
Write a function named longs(x,n) that takes a list argument x and an integer argument n. Your function should return a list of all the values of x whose length is n or more as determined by the len() function. For example, if x=[ "abc", "hi", "defg", "x"] then longs(x,3) should return ['abc', 'defg'].
def longs(x,n):
return [s for s in x if len(s) >= n]
x=[ "abc", "hi", "defg", "x"]
longs(x,3)
Write a function named lookup(d,l) that takes one dict argument named d and one list argument named l. Your function should return a list values from d using the keys given in l. For example if d = {'a': (1,1), 'b': 9, 'c':'see'} and l=['b','a'] then lookup(d,l) should return [9, (1, 1)].
d = {'a': (1,1), 'b': 9, 'c':'see'}
l=['b','a']
def lookup(d,l):
return [d[k] for k in l]
lookup(d,l)
Write a recursive function named appendlarger(a,b,n) that takes two list arguments , a and b and an integer argument n. Your function should append each value in b that is greater than n to the end of a. Your function does not have to return a value. For example if a=[1, 2, 3] and b=[4, 5, 6] then appendlarger(a,b,4) would set a to [1, 2, 3, 5, 6].
def appendlarger(a,b,n):
if len(b):
if b[0] > n:
a.append(b[0])
appendlarger(a,b[1:],n)
return
a=[1, 2, 3]
b=[4, 5, 6]
appendlarger(a,b,4)
a
Set the variable pat to a regular expression that matches a part number string created according to the following sequence:
- or .Hints: use \ to escape the special meaning of a character in a pattern. Use \\ to insert a \ in conventional string.
For example, re.search(pat,'ALA.00000') would return a match object but re.search(pat,'ALA-00000x') would not.
pat = r'^ALA[-\.][01][0-9]{4}$'
import re
re.search(pat,'ALA.00000'),re.search(pat,'ALA-00000x')
# 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 checkrecursive(f):
s=f.__name__
assert s in f.__code__.co_names, "{} is not recursive".format(s)
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():
x=randwords(10)
x0=copy.deepcopy(x)
n=randint(2,3)
y=longs(x,n)
z=[1 if x0[i] == s else 0
for i,s in enumerate(x0) if len(s)>=n]
assert len(z) == len(y) and all(z), \
f'longs{x,n} returns {y}'
def q2():
n=randint(3,5)
k=randwords(n)
v=choices(range(100),k=n)
d=dict(zip(k,v))
l=choices(k,k=n//2)
d0=copy.deepcopy(d)
l0=copy.deepcopy(l)
y=lookup(d,l)
assert ( len(y) == len(l0) and
all([d0.__getitem__(s) == y[i] for i,s in enumerate(l0)]) ),\
f'lookup{d0,l0} returns {y}'
def q3():
checkrecursive(appendlarger)
n=randint(5,15)
a=choices(range(20),k=randint(2,4))
b=choices(range(20),k=randint(2,4))
a0=copy.deepcopy(a)
b0=copy.deepcopy(b)
appendlarger(a,b,n)
assert a == a0+list(filter(lambda x:x>n,b0)),\
f'appendlarger{a0,b0,n} sets a to {a}'
def q4():
ok = [ r'ALA-00000',r'ALA.00000',r'ALA-19999', r'ALA-00000' ]
nok = [ r'ALB-00000',r'ALA00000',r'ALA-29999', r'ALA-0000', r'ALA-00000x' ]
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(f"Solution to question {i} may be correct.")
except Exception as e:
print(f"Failed check for question {i}: {e}")
examcheck()