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# Pause for Breath

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CS 65 // 2021-03-23

## Administrivia
- Exam 2 is due tonight
- 
 Rearranged the schedule a bit to complete the lists lab today
- 
 No assignment due Thursday

## Extra Credit Activities
- [Test Anxiety: Breath](https://calendar.drake.edu/event/test_anxiety_breath?utm_source=newsletter&utm_medium=email&utm_content=DETAILS&utm_campaign=Faculty-March-23#.YFoEI0hKhLw)
    + Thursday, 3/25 from 2pm to 3pm

## Extra Credit Activities
- [BLM Event](https://www.eventbrite.com/e/blmdrake-tickets-147650180665)
    + Two Drake alums are speaking on racial justice and equity with a Q&A to follow
    + Friday, 3/26 from noon to 1pm

# Questions
## ...about anything?

# Lists

## The `list` Type
- **Purpose:**
    + To manipulate collections of objects
- **Express:**
    + Lists are written: `[1,2,3]` and `["CS", 65]`
- **Operations:**
    + 
 `t[index]`, gets the object at the given `index`
    + 
 `t[start:end]`, gets the **sublist** that starts at index `start` and ends at index `end`
    + 
 `t1 + t2`, concatenates the two lists together

## The `list` Type

- **Other Operations**:
    + `len(t)`, gets the **length** of the list `t`
    + 
 `t.append(value)`: mutates `t` by adding `value` as a new element to the end of the list
    + 
 `t.sort()`: mutates `t` so that all of its elements are in ascending order
    + 
 `t.pop(index)`: mutates `t` by removing the element at the given `index`

## Mutability
- `list` is a **mutable** type
    + 
 It is possible to change the values a list contains **without creating a new list**
    + 
 `lst = [100, 101, 102]`
    + 
 `lst[0] = "abc"`, changes the first element
- 
 Other methods like `append`, `sort`, and `pop` also mutate the list rather than returning a new one

# Lab Time
- Navigate to and work through the **Lists** lab