Slides

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# Intro to Python
## Week 5
### Advanced iteration

---

## While you wait

#### Open these URLs:

- [NLPiA.org/fall26](https://NLPiA.org/fall26)
- [GitLab.com/mesa_python/fall26](https://GitLab.com/mesa_python/fall26)

---

## Review and practice

<html>
<script>hljs.configure({ 'languages': ['python'] });</script>
<table>
  <tr><th></th><th>Python</th></tr>
  <tr><td>GitLab and paths</td><td><pre><code class=hljs>cd ~/code
cd src/cisc179</code></pre></td></tr>
  <tr><td><code class=hljs>type</code>s, <code class=hljs>input</code>, <code class=hljs>if</code></td><td><code class=hljs>ans = float(input('1+2= '))</code></td></tr>
  <tr><td>Accumulation <code class=hljs>for</code> loop</td><td><pre><code class=hljs>x = 0
for i in range(3):
    x = x + i</code></pre></td></tr>
</table>
</html>

note:

1. Let's try to use your input/print/if/else skills to build you some study games for yourself
2. Let's review the accumulation pattern to make sure you understand how to use it well
3. In the lab today, you will practice these skills and start on you midterm project (due in 4 weeks)
4. Can you guess what that loop will output in the variable `x`?  **(2)**
5. What is it used for?

---

## [GitLab.com](https://gitlab.com)

- Can you create and edit files in GitLab?
- Can you find your work from last week?
- Create a file for your notes and code this week (wk5.py?).

#### Start on your midterm project

- In a new tab find the adventures directory (folder)?
- Create a new file named {your_mesa_username}.py

---

## [GitLab.com](https://gitlab.com)

```bash
$ cd ~/code
$ git clone https://gitlab.com/mesa_python/fall26
$ cd fall26
```

---

## New skills (Thurs)

<html>
<script>hljs.configure({ 'languages': ['python'] });</script>
<table>
  <tr><th></th><th>Python</th></tr>
  <tr><td>Advanced <code class=hljs>for</code> loops</td><td><pre><code class=hljs>x = 0
for i in range(3):
    if (i // 2) == (i / 2):
        x = x + i</code></pre></td></tr>
  <tr><td>List comprehensions</td><td><code class=hljs>[i for i in range(3)]</code></td></tr>
  <tr><td>Tuples</td><td><code class=hljs>(1, 2, 3)</code></td></tr>
</table>
</html>

note:

1. This week you will learn some powerful iteration and accumulation patterns
2. You'll also learn a about pattern called "list comprehension" which lets you expand lists like accordions or an infinite stack of Lego bricks: `[i for i in range(3)]` 
3. You'll start thinking about parentheses as hard plastic Easter eggs containing your data: `(1, 2, 3)`
4. Can you guess what that loop will output in the variable `x`?  **(2)**
5. What is it used for?

---

```python
>>> x = 0
... for i in range(3):
...     if (i // 2) == (i / 2):
...         x = x + i
... x
2
```

---

## Review ``types``s

- What **ARE** each of these things:
  - `print`
  - `input`
  - `random`
  - `if`
  - `else`

---

## Review

- Do you remember how to use:
  - `print`
  - `input`
  - `random`
  - `if`
  - `else`

---

## Flip a `coin`

- Can you generate a `random` value that is `0` or `1`?
- Can you use a random value in an `if` statement?
- Can you use `if` to decide who "won" a coin flip?
- Implement your coin-flip game as a function that returns `True` if user **won**

note:
- Advanced students should create a "best 2 out of 3" coin flip game using the accumulation pattern.
- Super-ambitious students should create rock_paper_scissors function to be used in a 2 out of 3 "face off".

---

## Stochastic parrots

- Imagine a digital-native child (or adult) watching cartoon reruns.
- Imagine they turn to Alexa or an AI and ask:
    - "Who is Donald?"
      - **OR**
    - "Complete the sentence: Donald"
- Watching cartoons is part of the context.

#### What else is relevant context?

---

## AI is coin-flipping

#### Stochastic Parrot

- Timnit Gebru
- Melanie Mitchell

But that's a dirty word you should never use at work among brogrammers.

---

## [Santa Fe Institute](https://santafe.edu)

- Understanding AI is **very** valuable
- But it's like religion and politics...

---

## Lab assignment (20 minutes)

- Can you generate a `random` value that is `0` or `1`?
- Can you use that value in a conditional expression (`if` statement)
- Can you create a coin flip game **function**?
- Implement your game as a function that returns `1` for the correct guess.

```python
def flip_a_coin():
    user_ans = input(...)
    ...
```

---

## Let's flip a coin!

```python
def flip_a_coin():
    user_ans = input('Call "H" for heads, "T" for tails: ')
    zero_or_one == random.randint(0, 1)
    coin_flip = 'T'
    if zero_or_one == 1:
        coin_flip = 'H'
    print('The coin flip came up', coin_flip)
    if str.upper(user_ans) == coin_flip:
        print('Good job! You earned a `+1` !!')
        return 1
    print(f'You answered {user_ans}. That is not correct.')
```

note:
- You can even use the `eval` and `exec` functions to check the answer automatically

---

## Coin flip game

```python
def play_flip_a_coin(rounds):
    """ Play several rounds of flip_a_coin against the computer """
    wins = 0
    for round in range(rounds):
        wins += int(flip_a_coin())
    return wins
```

---

## Attendance

1. **Read**   the code and comments
2. **Predict**   what Python interpreter will do 
3. **Write**   your `name` and `answer` on the board
<br>
<br>
```python
>>> # replace "Professor" with YOUR first name
>>> name = "Professor"
>>> answer = 0 + (len(name) > 4) and (len(name) < 7)
>>> answer = answer + 'a' in name + 'a' in name.lower()
>>> answer = answer + 'e' in name
>>> answer = answer + 'i' in name
>>> answer
1
```

4. **Check** your answer. (Hint: use an interpreter)

note:
- Read the code, imagining your first name in place of the string literal "Professor"
- Predict what the python interpreter will do
- Write your `name` and answer on the board
- Check your understanding of the code by running it one line at a time (active learning)

---

## Lab

- Check and correct your answer
- Write a function to check both you and your neighbors' answers
- Advanced: Copy your function to  **all** unique vowels
- Thurs: Copy your function to count **all** unique vowels

---

## One approach

```python
NAMES = 'Professor Adam Andrew Anthony Bryce Enrique Ethan Gilead Girot '
NAMES = NAMES + 'Hugo James Kaleb Karim Luis Nesim Ruth Ryu Santos Sergio Tyler Xin Zach'

def check_names(names=NAMES):
    for name in names.split():
        answer = len(name) > 4
        answer = answer + ('a' in name) 
        answer = answer + ('a' in name.lower())
        answer = answer + ('e' in name)
        answer = answer + ('i' in name)
        print(answer, name)
```

---

```python
>>> check_names
1 Professor
2 Adam
3 Andrew
1 Anthony
2 Bryce
2 Enrique
3 Ethan
3 Gael
5 Gilead
2 Girot
0 Hugo
4 James
4 Kaleb
4 Karim
1 Luis
3 Nesim
0 Ruth
0 Ryu
3 Santos
3 Sergio
2 Tyler
1 Xin
2 Zach
```

---

## Advanced example

```python
def check_names_advanced(names=NAMES):
    answers = []
    count = 0
    for name in names.split():
        count += len(name) > 4 and len(name) < 7
        count += 'a' in name + 'a' in name.lower()
        count += 'e' in name
        count += 'i' in name
        answers += [str(count) + " " + name]
    return answers
```

---

## Example vowel counter

```python
def count_unique_vowels(text):
    """ Count the number of unique (different) vowels used in a text str

>>> count_unique_vowels('supercalafragalistic')
    4
    """
    num_unique_vowels = 0
    for vowel in 'aeiou':
        num_unique_vowels += vowel in text
    return num_unique_vowels
```

note:
- Remember where you see that word "unique" a lot at the Python console?
- Another word for "unique" is "different" but that is a bit ambiguous

---

## Example answer checker

[![wk5/wk5.py](./wk5/wk5-1.png)](./wk5/wk5.py)

[https://nlpia.org/wk5/wk5.py](./wk5/wk5.py)

---

## My attendance checker

[![wk5/wk5.py](./wk5/wk5-2.png)](./wk5/wk5.py)

[https://nlpia.org/wk5/wk5.py](./wk5/wk5.py)

---

## My vowel checker

[![wk5/wk5.py](./wk5/wk5-3.png)](./wk5/wk5.py)

[https://nlpia.org/wk5/wk5.py](./wk5/wk5.py)

---

## Lab: Gamify your learning!

Create a text adventure "room" that requires you to answer a Python programming question.

```python
correct_ans = 5
print('Evaluate the Python expression below:')
print('>>> 2 + 3')
user_ans = input("")
print()
if user_ans == correct_ans:
    print('Good job! You earned a `+1` !!')
else:
    print(f'You answered {user_ans}. That is not correct.')
```

- Read the code above, to see if you can see what it does.
- Run the code above to see if it gives what you expected!
- Fix any bugs you find. 
- Add another Python code-reading question

---

## Mob programming

```python
def ask_python_question(python_expression, correct_answer):
    print('Evaluate the Python expression below:')
    print('>>>', python_expression)
    user_ans = input("")
    print()
    if user_ans == str(correct_ans):
        print('Good job! You earned a `+1` !!')
        return 1
    print(f'You answered {user_ans}. That is not correct.')
    return 0
```

note:
- You can even use the `eval` and `exec` functions to check the answer automatically

---

## Coin flip game

```python
def coin_flip_game():
    user_ans = input('Call "H" for heads, "T" for tails: ')
    zero_or_one == random.randint(0, 1)
    coin_flip = 'T'
    if zero_or_one == 1:
        coin_flip = 'H'
    print('The coin flip came up', coin_flip)
    if str.upper(user_ans) == coin_flip:
        print('Good job! You earned a `+1` !!')
        return 1
    print(f'You answered {user_ans}. That is not correct.')
    return 0
```

note:
- You can even use the `eval` and `exec` functions to check the answer automatically

---

## Assignment requirements

- Use `if`, `elif`, `else` to check 3 possible conditions
  - User needs help understanding how to play
  - User wants to exit the game
  - User wants to play your game
- Use `print` to let the user know what just happened.
- Use `input` to ask the user what they want to do next.

---

## Simplest approach

```python
def play_game():
    print("Welcome to ____, a text adventure!")
    print("You see a house...")
    go_inside_answer = input("Go into house? ")
    if ___ in go_inside_answer:
        print("Inside, you see ...")
        ...
    elif ___ in go_inside_answer:
        print("Exiting the game...")
        return
    else:
        print("To play the game you need to ...")
        play_game()
```

---

## Add an "entered house" room? (next week)

```python
if ___ in go_inside_answer:
    print("Inside, you see ...")
    if ___ in go_to_bedroom_ans:
        print("You see ...")
        go_to_closet_ans = input("Go into closet? ")
    elif:
        print("You don't see anything...")
        ...
    else:
        print("I don't understand. Try again ...")
elif ___ in go_inside_answer:
    print("Exiting the game...")
else:
    print("To play the game you need to ...")
play_game()  # rerun your main function
```

---

## But your function gets too long!

```python
print("You see ...")
go_inside_answer = input("Go inside house? ")
if ___ in go_inside_answer:
    print("You see ...")
    go_to_bedroom_ans = input("Go into bedroom? ")
    if ___ in go_to_bedroom_ans:
        print("You see ...")
        go_to_closet_ans = input("Go into closet? ")
        if ___ in go_to_closet_ans:
            print("At back of wardrobe you see a loose panel.")
            secret_door_ans = input("What do you do? ")
            if ___ in secret_door_ans:
                print('You found...')
                print('You win!')
            elif:
                print("You don't see anything...")
                ...
            else:
                print('You die of boredom.')
                ...
        elif ...:
            ...
        else:
            ...
    elif ...:
        ...
    else:
        ...
elif ___ in go_inside_answer:
    ...
else:
    ...
```

---

## Room functions

- Break your game into "rooms"
- Create one function for each room
- Each function can either:
  - Return the name of the next room
  - Call the function for the next room

---

## Conditional expression review

- Remember your order of operations and the correct way to read Python statements
- Think about the types of objects as you evaluate each expression
- Remember your debugging process
- Try to improve it by asking additional questions and keeping track of a total score
- If you need more practice on any of these, think of a good gameified question you can ask yourself!

note:

1. Do you remember the order of operations rules?
2. What type is (Whenever you see an `input` expression what type do you expect it to return?)
3. What type is

2. You'll learn how to read and write conditional expressions
3. You'll learn how to use conditional expressions in if statements
4. You'll learn how to sweeten your code with `or` in variable assignments