To get credit for this lab, you will need to enter your names and netids, and the answers to several questions on an online form.
Complete this form for credit for lab 4
(the same questions are accessible here as well).
| string method | purpose |
|---|---|
| s.upper() | returns string upper case version of string s |
| s.count(sub) | returns int number of (non-overlapping) occurrences of sub in s |
| s.endswith(sub) | returns boolean depending on whether s ends with sub |
| s.find(sub) | returns int: first index at which sub occurs in s or -1 if no occurrences |
| s.split() | returns list of s split on whitespace |
| s.split(sep) | returns list of s split on sep, a delimiter |
| s.strip() | returns copy of s withOUT leading and trailing whitespace |
| list method | purpose |
|---|---|
| lst.count(elt) | returns number of occurrences of elt in lst |
| lst.index(elt) | returns first/least index at which elt occurs in lst, generates error if elt not in lst |
| lst.append(elt) | append elt to end of lst, None returned |
Functions are applied to objects. For example, len returns
an int: the length of a string or list or other
sequence/iterable. So len("apple") is 5 and
len([1,2,3]) is 3.
Other functions for lists include: sum (returns total, an int, of elements in a list); max,min which return largest and smallest elements in a list; sorted which returns a sorted version of a list; reversed which returns a reversed version of a list.
For example:
| function call | result returned | type returned |
|---|---|---|
| len([1,2,3,"apple"]) | 4 | int |
| max([5,4,1,2,9,3]) | returns 9 | same as list elements |
| max(["ape", "bee", "zebra", "wildebeast"]) | "zebra" | same as list elements |
| min([5,4,1,2,9,3]) | returns 1 | same as list elements |
| sorted([5,4,1,2,7]) | [1,2,4,5,7] | list |
| reversed([1,2,3,6]) | [6,3,2,1] | list |
For each of the following questions, keep in mind that the variable in the question could represent a string or a list.
Answer these questions on the online form.
max returns the maximal value of a string
as well as a list. What is max("science") and why?
reversed(sorted([5,4,1,2,8])) and
why?
sorted(lst).index(min(lst)) for
any list lst? Why? What's the value if
min is replaced by max?
str.endswith(str[-3:]) True?
st.upper().endswith(st) True?
(Provide a specific example of when it's true and try to generalize)
in operator determines if its left operand occurs
in its right operand and returns a boolean value. This means
'a' in 'stranger' evaluates to True. What
is the value of 5 in [1,2,3,4]?
st[0:2] in st is False?
(Provide a specific example of when it's true and try to generalize)
st[0:2]*2 in st is True?
(Provide a specific example of when it's true and try to generalize)
lst.count(lst[0]) the same
as the value of len(lst) for a list lst?
(Provide a specific example of when it's true and try to generalize)
In the following three examples, a higher fee is suppose to be assigned to a higher speed. For each of the following three choices, decide if the higher fee is assigned to the higher speed and if not explain why. For example, if the speed is 85, is the fee assigned always 60?
# Example A
speed = 85
fee = 0
if speed > 35:
fee = 20
if speed > 50:
fee = 40
if speed > 75:
fee = 60
print fee
# Example B
speed = 85
fee = 0
if speed > 75:
fee = 60
if speed > 50:
fee = 40
if speed > 35:
fee = 20
print fee
# Example C
speed = 85
if 35 < speed and speed <= 50:
fee = 20
if 50 < speed and speed <= 75:
fee = 40
if 75 < speed:
fee = 60
print fee
To which of the following is this expression equivalent:
not ((x > y) and (y <= 3))
(x > y) and (y <= 3)(x > y) or (y <= 3)(x < y) or (y >= 3)(x <= y) or (y > 3)(x <= y) and (y > 3)
This means 1800, 1900, and 2100 are not leap years but 2000 and 2004 are leap years.
Which of the following implementations of a
method is_leap returns true if year is a leap year and
false otherwise. For each one list whether or not it is correct.
If a method is not correct, provide a value for year for which it returns the wrong value.
def is_leap1 (year):
if year % 400 == 0: return True
if year % 100 == 0: return False
if year % 4 == 0: return True
return False
def is_leap2 (year):
return year % 400 == 0 or (year % 4 == 0 and year % 100 != 0)
def is_leap3 (year):
if year % 100 == 0: return False
if year % 400 == 0 or year % 4 == 0: return True
return False
all_same that returns true only if all three of the given values are the same. For example, a call to all_same with the values 3, 128, 255 should return False; while the values 128, 128, 128 should return True. def all_same (value1, value2, value3):
You'll work on loops and strategies to solve one APT: ScoreItYahtzee which is part of the apt-3 group of APTs, so you can snarf them for testing. (note the filename for this APT is ScoreIt.py).
maxPoints return for the call
maxPoints([2,2,4,5,4]) and why?
toss is given
by the expression toss.count(1) --- what expression gives
the number of 2's that occur in the list toss?
best correctly to
be the best score for a list toss if the only values in the
list are 2 or 4. Explain in words why the second if
CANNOT be an elif --- provide an example that would fail
to set best correctly for a list of only 2's and 4's if
an elif statement is used (explain your reasoning).
roll ?
After answering the questions together, you can individually work on completing this APT.
Do this section if you have time, if not no worries...
Discuss strategies for solving the APT Silver Distance. Do not write code together, just discuss how one might go about solving this problem.
There is nothing for the online form for this part.