<style>
/* Mesa's colors in ./mesa-custom.css: navy=#023867, link-blue: #00529c, gold: #fdb930, background: white */
</style>

# Intro to Python

<br>

## Week 3 Tues

<br>

## `def`ining better functions

## <span> and `for` loops </span>

<br>

#### Virtual Office Hours 10AM & 7PM:
#### [sdccd-edu.zoom.us/my/dlane](https://sdccd-edu.zoom.us/my/dlane) 
#### ``[slides.nlpia.org](https://slides.nlpia.org/)``

---

## Attendance

1. walk up to the whiteboard
2. write your first name
3. write a keyword or function name
4. in python that's: ``f'{your_first_name}: {keyword_or_function}'``

## Hint: Use Sublime Text

Hit `[Ctrl]+[P]` to find your `wk2.py` file <br>  <br>
   **OR**  <br> <br>
Hit `[Ctrl]+[Shift]+[F]`, type part of a Python keyword, then hit `[Enter]`

note:

Be prepared to explain to the class why you like it.

---

## `str.`_[TAB]_      active learning

---

```python
>>> text = 'hello world'
>>> text
```

```
'hello world'
```

---

```python
>>> text = 'python rules'
>>> text
```

---

```python
>>> text = 'python rules'
>>> text
'python rules'
```

note:
- that's why it is called a string literal
- because the variable contains literally the same value as the python expression
- the root of literal is the same as for literate and literature
- this is the real meaning of "literally"
- the slang meaning is "honestly" or "truly"

---

```python
>>> str.title('hello world')
```
`'Hello World'`

```python
>>> print('hello world'.title())
```
`Hello World`

---

```python
>>> str(1e6)
```

```python
'1000000.0'
```

note:
- why single quotes?
- what happens if you `

---

```python
>>> text = 'Hello World!'
>>> is_enthusiastic = '!' in text
>>> is_enthusiastic
```

```
True
```

---

```python
'hello' == 'Hello'
```

```
False
```

```python
>>> 'ello' in 'Hello'
```

```
True
```

note:
- Hopefully you were able to predict these results

---

## How can you learn about `str.replace()` ?

```python
help(str.replace)
```

```
...
replace(self, old, new, count=-1, /) unbound builtins.str method
    Return a copy with all occurrences of substring old replaced by new.

count
        Maximum number of occurrences to replace.
        -1 (the default value) means replace all occurrences.
...
```

---

## function signature for `str.replace()` ?

```python
str.replace(self, old, new, count=-1, /)
```

---

## How many arguments does `str.replace()` have?

```python
>>> len(self, old, new, count)
```

```
TypeError: len() takes exactly one argument (4 given)
```

---

## How many <red>MANDATORY</red> arguments does `str.replace()` have?

```python
>>> len(self, old, new)
```

---

## How many <red>MANDATORY</red> arguments does `"Hello World!".replace()` have?

```python
>>> "Hello World!".replace(old='Hello', new='Bye')
'Bye World!'
```

```python
>>> str.replace("Hull", 'l', 'k')
>>> 'Hull'.replace('l', 'k')
```

```
'Hukk'
```

---

## `str.replace` skills

```python
>>> "Hull".replace('ll', 'lk')
```

```
'Hulk'
```

---

```python
str.split()
str.join()
```

note:
- Hopefully you've already seen these in your playful `str.[TAB][TAB]` exploring

---

## Announcements

### [syllabus](https://sdccd.instructure.com/courses/2505751/assignments/syllabus)

- Attendance drops Sunday and Monday
- Labor Day on Monday!
- Give me feedback!

### Zoom Office Hours Monday 10AM & 7PM
### [sdccd-edu.zoom.us/my/dlane](https://sdccd-edu.zoom.us/my/dlane)

note:
- good news and bad news
- I start dropping absentee students on Sunday
- Labor Day on Monday!
- I will be at zoom office hours on Monday
- Show up at office hours if you have not attended most of our class sessions
- Making attendance is not enough, you need to participate for the entire class

---

## Assignments due Sunday

- [Runestone.Academy Module 2](https://runestone.academy/assignment/student/chooseAssignment)
- [Canvas Module 2](https://sdccd.instructure.com/courses/2505751/modules)

note:
- next week [GitLab.com/mesa_python/fall26](https://gitlab.com/mesa_python/fall26)

---

## ``def``ine `print_and_return()`

```python
def print2(text):
    return print(text)
```

note:
- improve python style
- what does `print()` return
- what does our version of `print` return
- add a docstring

---

## Hints

- improve python style
- what does `print()` return?
- what does our version of `print` return
- add a docstring

---

```python
def print_and_return(text):
    print(text)
    return text
```
---

## Hints

- add a ``__doc__``string (a special ``# comment``) first!
- make it useful in a text adventure or conversation
- add another argument

---

```python
def greet(greeting, name):
    """ Greet the user by name enthusiastically!

>>> greet('Hi', 'bob')
    'Hi Bob!'
    """
    text = greeting + ' ' + name + '!'
    print(text)
    return text
```

[starter code](./wk2/wk2.py)

---

```python
for i in range(3):
    print(i)
```

[starter code](./wk2/wk2.py)

note:
- Which words are keywords?
- Notice any new punctuation or whitespace?
- Which words are built-in function names?
- Which words are variable names?
- Which words are literal values?

---

Have a play with the new keywords and functions for this week:

- `def`
- `return`
- `for`
- `range`

note:
- Which of these are Python keywords?
- Which are built-in Python functions?

---

Advanced looping (__iteration__) keywords:

- `continue`
- `break`

---

### Links

1. [slides.nlpia.org](https://slides.nlpia.org)
2. [starter code](./wk2/wk2.py)