Introduction to Python
Learning a Not-So-Foreign Language
Translate the following expressions.
________________
_________________
________________
_________________
_________________
_________________
_________________________________
_________________________________
_________________________________
def distinct(string):
for___in________________________:
for___in________________________:
if___________________:
return________________
return__________________
What is the difference between print and return?
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Monty Python’s Practice Circus
1. Fill in the fizzbuzz function so that it does the following:
- Print out the numbers 1 through 100
- If the number is divisible by 3, print “fizz”.
- If it is divisible by 5, print “buzz”.
- If it is divisible by 15, print “fizzbuzz”.
def fizzbuzz():
foo == 5
foo = 5
foo += 5
len(“word”)
“word”[2]
“h”+”i”
for i in range(1, 11):
print(i)
i
range(0, len(string) - 1)
range(i + 1, len(string))
j
string[i] == string[j]
False
True
Print is similar to “say” in Snap: it just displays a value. Return on the other hand, is like report: it attributes a value to a function call.
for i in range(1, 101):
if i % 15 == 0:
print(“fizzbuzz”)
elif i % 5 == 0:
print(“buzz”)
elif i % 3 == 0:
print(“fizz”)
else:
print(i)
Alternate solution:
def fizzbuzz():
s = “”
for i in range(1, 101):
if i % 3 == 0:
s += “fizz”
if i % 5 == 0:
s += “buzz”
if s == “”:
print(i)
else:
print(s)
2. Write a function that will count the number of times a letter appears in a string. For
example, if the string was ”tinny”, and we were going to find the number of times the
letter “n” appears in the string, our function will return 2. If we tried to find the number
of times “d” appeared in the string, our function would return 0.
Try writing this iteratively and recursively. Finish one way? Try it the other way!
def
find_num_of_letters
(str, letter):
def find_
num_of_letters
(str, letter):
Bugs? What Bugs?
We decide to write a function called floor_divide which will report the number of
times a smaller number can fit into a bigger number. We know our algorithm is right but
we notice there are a lot of Python syntax bugs in our code. Identify and fix them!
def floor_divide(big_num, small_num):
if small_num = 0:
return You cannot divide by zero!
current_num = small_num
num_times = 0
while current_num <= big_num
current_num = current_num + small_num
num_times = num_times + 1
return num_times
Extra for Experts: Falling Factorial
Write a function falling, which is a “falling” factorial that takes two arguments, n and k,
and returns the product of k consecutive numbers, starting from n and working
downwards. For example, falling(10, 3) will return 720 (10 * 9 * 8).
def
falling
(n
, k
):
#iterative
count = 0
for item in str:
if item == letter:
count += 1
return count
#recursive
if len(str) == 0:
return 0
elif str[0] == letter:
return 1 + find_num_of_letters(str[1:], letter)
else:
return find_num_of_letters(str[1:], letter)
if small_num == 0:
String must be in
quotes:
return “You cannot
divide by zero!”
needs colon after big_num
if k == 0:
return 1
else:
return n * falling(n - 1, k - 1)
