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.
Write a function named select that takes two list arguments named x and s. Your function should return a list consisting of all the values of x for which the corresponding value of s is true. For example, if x=[1, 'a', -1, "xyz"] and s=[True, 0, [], 3] your function should return [1, 'xyz']. You may assume both arguments are the same length.
def select(x,s):
return [xi for xi,si in zip(x,s) if si]
x=[1, 'a', -1, "xyz"]
s=[True, 0, [], 3]
select(x,s)
Write a function named lookup that takes one dictionary argument named d and a list argument named l. The keys in d are strings and the values are integers. The values in l are strings. Your function should return a list of the values in d corresponding to the strings in l. For example if d = { 'add': 3, 'sub': 9, 'jmp': 32 } and l = ['sub', 'add', 'add'] then lookup(d,l) should return [9, 3, 3]. You may assume all the strings in l are keys in d.
def lookup(d,l):
return [d[s] for s in l]
d = { 'add': 3, 'sub': 9, 'jmp': 32 }
l = ['sub', 'add', 'add']
lookup(d,l)
Write a recursive function named addsquares that takes a list argument named x and an integer argument m. Your function should append the values $m^2,(m-1)^2, \ldots$, 1$ to x. Your function does not return a value (it modifies x in place). For example if x=[1,2,3] then after calling addsquares(x,3) x would be equal to [1,2,3,9,4,1].
def addsquares(x,m):
if m < 1:
return
else:
x.append(m*m)
addsquares(x,m-1)
x=[1,2,3]
addsquares(x,3)
x
Set the variable pat to a regular expression that matches part numbers created according to the following sequence:
For example, re.search(pat,'JSM1SAH-12V') would return a match object but re.search(pat,'JSM1SAH-') would not.
pat=r'^(JSM|CP)[1234]S?AH?-(12|24)V$'
import re
print(re.search(pat,'JSM1SAH-12V'))
print(re.search(pat,'JSM1SAH-'))
# exam validation code; do not modify
def examcheck():
def randwords(n):
from random import randint
return [''.join([chr(randint(97,122)) for i in range(randint(2,5))])
for j in range(n)]
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, choices
import copy
n=randint(4,7)
s=choices([True, False, 0, 1, [], [1]],k=n)
x=randwords(n)
x0=copy.copy(x)
y=select(x,s)
assert all(x[i] in y for i in range(n) if s[i]), \
"for x={} and s={} incorrect values included in result={}".format(x,s,y)
assert len(y) == len([i for i in s if i]),"wrong number of values in result"
def q2():
from random import randint, shuffle
n=randint(4,6)
l=randwords(n)
m=list(range(10,10+n))
shuffle(m)
d={s:m[i] for i,s in enumerate(l)}
r={m[i]:s for i,s in enumerate(l)}
x=lookup(d,l)
assert all(r[n] == s for s,n in zip(l,x))
def q3():
from random import randint
import copy
checkrecursive(addsquares)
n=randint(1,3)
m=randint(2,4)
x=list(range(n))
x0=copy.copy(x)
addsquares(x,m)
sumsq=int((m/6)*(m+1)*(2*m+1)+0.5)
msg="addsquare(x={},{}) results in x={}".format(x0,m,x)
assert x[:n] == x0, "initial values changed: "+msg
assert sum(x[n:]) == sumsq, "wrong squares: "+msg
def q4():
ok=['JSM1SAH-12V', 'CP4A-24V', 'JSM4AH-12V', 'CP3SA-12V', 'JSM2A-24V' ]
nok=[' JSM1SAH-12V', 'JS1SAH-12V', 'JSM1SAH-', 'CPA-12V', 'CP1SA-24' ]
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()