Python Foundations, Lab 2: Practice with Flow Control¶

Instructor: Wesley Beckner

In this lab we will continue to practice flow control.

➿ L2 Q1: Print and For Loops¶

Create a Pyramid Using for loops

Part A¶

Example output:

* 
* * 
* * * 
* * * * 
* * * * *

# Code Cell for L2 Q1 A
for i in range(1,6):
  print('* '*i)

* 
* * 
* * * 
* * * * 
* * * * *

Part B¶

Example output:

        * 
      * * 
    * * * 
  * * * * 
* * * * *

# Code Cell for L2 Q1 B
j = 6
for i in range(1,j):
  print('  '*(j-i) + '* '*i)

          * 
        * * 
      * * * 
    * * * * 
  * * * * *

Part C¶

Example output:

         * 
        * * 
       * * * 
      * * * * 
     * * * * *

# Code Cell for L2 Q1 C
j = 6
for i in range(1,j):
  print(' '*(j-i) + '* '*i)

     * 
    * * 
   * * * 
  * * * * 
 * * * * *

🔙 L2 Q2: Conditionals and For Loops¶

Complete the Fibonacci sequence up to the 10^th place using any or all of the following:

for
if elif else
append
range

The Fibonacci sequence with indices:

0
1
1
2
3
5
8
etc..

Example input:

index = 9

Example output:

Index: 9
Value: 34

list(range(1,2))

[1]

# Cell for L2 Q2
index = 9
fib = []

for i in range(index+1):
  if i == 0:
    fib.append(0)
  elif i < 3:
    fib.append(1)
  else:
    fib.append(fib[-2] + fib[-1])

print("Index: {}".format(i))
print("Value: {}".format(fib[-1]))
print(fib)

Index: 9
Value: 34
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

🧺 L2 Q3: Practice with Collections¶

concatenate the following dictionaries to create a new one. If you need to, refer to documentation for python dictionaries!

Input:

dict1={1:10, 2:20}
dict2={3:30, 4:40}
dict3={5:50, 6:60}

Output:

new_dict={1:10, 2:20, 3:30, 4:40, 5:50, 6:60}

# Cell for L2 Q3
dict1={1:10, 2:20}
dict2={3:30, 4:40}
dict3={5:50, 6:60}

new_dict = {}
new_dict.update(dict1)
new_dict.update(dict2)
new_dict.update(dict3)

print(new_dict)

{1: 10, 2: 20, 3: 30, 4: 40, 5: 50, 6: 60}

🐝 L2 Q4 The FizzBuzz task¶

Let's do this! FizzBuzz is our first task for this session. FizzBuzz is a common toy programming problem that is often used in software engineering job interviews. Today, we are not after the most compact, most clever, or even the most beautiful solution. Your goal is to solve the problem using for and if as your primary tools. You will likely also want to use the % operator. Before we describe FizzBuzz, let's talk about the moduluo operation.

If you recall from session 1, you may have experimented with the modulus or % operator. When used between two integer values, it returns the integer remainder of division. Let's start with a simple example of 5 modulo 3:

5 % 3

5 % 3

Let's do another example... What is the result of the following:

10 % 5

10 % 5

Now, on to FizzBuzz. No it isn't the high-test caffeine cola you might need right now. Instead, it is a challenge to output certain text as the code iterates over elements in a list. Here is the formal definition of the problem that we will use today.

"Write a program that prints the numbers from 1 to 100. But for multiples of three print Fizz instead of the number and for the multiples of five print Buzz. For numbers which are multiples of both three and five print FizzBuzz."

To get started, you will need a for loop and it will probably use a range list. Inside of the for loop, you will likely have at least two if statements that use the % operator followed by a print.

# Cell for L2 Q4
for i in range(1,101):
  if (i % 3 == 0) and (i % 5 == 0):
    print("FizzBuzz")
  elif i % 3 == 0:
    print("Fizz")
  elif i % 5 == 0:
    print("Buzz")
  else:
    print(i)

1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz
16
17
Fizz
19
Buzz
Fizz
22
23
Fizz
Buzz
26
Fizz
28
29
FizzBuzz
31
32
Fizz
34
Buzz
Fizz
37
38
Fizz
Buzz
41
Fizz
43
44
FizzBuzz
46
47
Fizz
49
Buzz
Fizz
52
53
Fizz
Buzz
56
Fizz
58
59
FizzBuzz
61
62
Fizz
64
Buzz
Fizz
67
68
Fizz
Buzz
71
Fizz
73
74
FizzBuzz
76
77
Fizz
79
Buzz
Fizz
82
83
Fizz
Buzz
86
Fizz
88
89
FizzBuzz
91
92
Fizz
94
Buzz
Fizz
97
98
Fizz
Buzz

For advanced folks, a hint here is that you might be able to avoid some if statements by using the end parameter to the print function. Notice how these two cell blocks output differently.

print("Fizz")
print("Buzz")

In another cell:

print("Fizz", end="")
print("Buzz", end="")
print()

for i in range(1,101):
  if i % 3 == 0:
    print("Fizz", end='')
  if i % 5 == 0:
    print("Buzz", end='')
  if (i % 3 != 0) and (i % 5 != 0):
    print(i, end='')
  print()

1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz
16
17
Fizz
19
Buzz
Fizz
22
23
Fizz
Buzz
26
Fizz
28
29
FizzBuzz
31
32
Fizz
34
Buzz
Fizz
37
38
Fizz
Buzz
41
Fizz
43
44
FizzBuzz
46
47
Fizz
49
Buzz
Fizz
52
53
Fizz
Buzz
56
Fizz
58
59
FizzBuzz
61
62
Fizz
64
Buzz
Fizz
67
68
Fizz
Buzz
71
Fizz
73
74
FizzBuzz
76
77
Fizz
79
Buzz
Fizz
82
83
Fizz
Buzz
86
Fizz
88
89
FizzBuzz
91
92
Fizz
94
Buzz
Fizz
97
98
Fizz
Buzz