Python Logic

class: middle

# .eight[CSET 160:]
## .eight[Web Development II]

---
class: middle

# Python Logic

---

# Agenda

1. [ ] [Imports](#imports)
2. [ ] [Reviewing Basic Logic](#logic)
3. [ ] [Python Conditionals](#conditionals)
4. [ ] [Branching Logic](#branching)

---

# [Exercise 20](https://github.com/ts-cset/cset-160/blob/master/python/ex20.py)

This one is a nice warmup, just write it and run it. You should understand everything it's doing.

---
name: imports

# [Exercise 21](https://github.com/ts-cset/cset-160/blob/master/python/ex21.py)

This one isn't as simple. You'll write it, but you won't run it. You'll *import* it into the REPL and run the functions yourself.

(Although, you might still want to run this file to make sure you typed it correctly.)

Open the REPL on your Terminal with:
```sh
$ python3
>>>
```

---

# Exercise 21

Open the REPL and enter these lines, one at a time:

```python
>>> import ex21
>>> sentence = "All good things come to those who wait."
>>> words = ex21.break_words(sentence)
>>> words
>>> sorted_words = ex21.sort_words(words)
>>> sorted_words
```
There's more, keep going on the next slide...

---

# Exercise 21

```python
>>> ex21.print_first_word(words)
>>> ex21.print_last_word(words)
>>> words
>>> ex21.print_first_word(sorted_words)
>>> ex21.print_last_word(sorted_words)
>>> sorted_words
>>> sorted_words = ex21.sort_sentence(sentence)
>>> sorted_words
>>> ex21.print_first_and_last(sentence)
>>> ex21.print_first_and_last_sorted(sentence)
```

---

# Exercise 21

- Did you get the output you expected?
- Try typing .eight[help(ex21)] and .eight[help(ex21.break_words)] in the REPL. Does that help explain those odd triple quoted strings? These are called *documentation comments*.
- Close the REPL and try it again, this time typing .eight[from ex21 import *]. The asterisk means "import everything" from the module. How does this change how we call the functions?

---

# [Exercise 22](https://github.com/ts-cset/cset-160/blob/master/python/ex22.py)

This last warmup is a little different. This is the *one* time you get to copy/paste code. Exercise 22 is broken. Copy the file and try to fix it.

---
class: middle, center

# .eight[What do we know so far?]

---
name: logic

# Logical Terms

- true / false
- and
- or
- not
- equal / not equal
- greater / less than
- greater / less than or equal to

---

# Truth Tables

An easy way to understand logic with simple memorization.

The simplest is with .eight[not].

```md
| NOT       | RESULT |
| ---       | ---    |
| not False | True   |
| not True  | False  |
```

---

# Truth Tables

```md
| OR             | RESULT |
| ---            | ---    |
| True or True   | True   |
| True or False  | True   |
| False or True  | True   |
| False or False | False  |
```

---

# Truth Tables

```md
| AND             | RESULT |
| ---             | ---    |
| True and True   | True   |
| True and False  | False  |
| False and True  | False  |
| False and False | False  |
```

---

# Truth Tables

```md
| NOT OR               | RESULT |
| ---                  | ---    |
| not (True or True)   | False  |
| not (True or False)  | False  |
| not (False or True)  | False  |
| not (False or False) | True   |
```

---

# Truth Tables

```md
| NOT AND               | RESULT |
| ---                   | ---    |
| not (True and True)   | False  |
| not (True and False)  | True   |
| not (False and True)  | True   |
| not (False and False) | True   |
```

---

# [Exercise 23](https://github.com/ts-cset/cset-160/blob/master/python/ex23.txt)

This is just a text file, not a python script, so you don't have to write it down and run it.

Instead, try to figure out the Boolean result from each expression. Write them down somewhere.

Then open up the Python REPL and evaluate each line. Can you get them all right?

---
name: conditionals

# [Exercise 24](https://github.com/ts-cset/cset-160/blob/master/python/ex24.py)

Conditionals!

- This should be very familiar.
- What happens if the code block under an if-statement is not indented?
- Play around with the variables and conditions and try to get other lines to print.

---

# [Exercise 25](https://github.com/ts-cset/cset-160/blob/master/python/ex25.py)

- Conditionals use the same colon and indent syntax as functions
- Try to add some more complex Boolean expressions, like using .eight[and] or .eight[or].

---
name: branching

# [Exercise 26](https://github.com/ts-cset/cset-160/blob/master/python/ex26.py)

- Learning conditions finally makes our scripts more interesting with different branches of codes.
- Add some more options to this game and then have a friend play it.
- Now try to make an entirely new game.