W1: Intro to Computing and Class Logistics

Welcome!

Introductions

  • Who am I?
  • What is DaSL? And TAs!

  • Who are you? (Online people, in Chat)

    • Name, pronouns, group you work in

    • What you want to get out of the class

    • Favorite autumn activity

Goals of the course

  • Fundamental concepts in programming languages: How do programs run, and how do we solve problems effectively using functions and data structures?

  • Data science fundamentals: How do you translate your scientific question to a data wrangling problem and answer it?

    Data science workflow

Culture of the course

  • Challenge: We sometimes struggle with our data science in isolation, unaware that someone two doors down from us has gone through the same struggle.
  • We learn and work better with our peers.
  • Know that if you have a question, other people will have it.
  • Asking questions is our way of taking care of others.

We ask you to follow Participation Guidelines and Code of Conduct.

Words of Encouragement

  • Be gentle with yourself
  • Learning data science and programming can be inherently difficult
  • It’s not you, it’s the subject

Breaks Are Super Helpful

Format of the course

  • Hybrid, and recordings will be available.
  • 1-2 hour exercises after each session are encouraged for practice.
  • Office Hours Fridays 10am - 11am PT.
  • Online discussion via Slack / Teams (use office hours teams meeting).

Quick Look at the Website

https://hutchdatascience.org/Intro_to_R

Content of the course (by week, roughly)

  1. *Intro to Computing
  2. Data structures
  3. *Data visualization
  4. Learning Community Session (optional)
  5. *Data wrangling 1
  6. Data wrangling 2
  7. *Learning Community Session (optional)
  8. Wrap up / Loading your own data / Code-a-thon prep

In person: I will be on-campus on the * dates. Other dates, you are free to attend in the DaSL lounge.

Full info is here: https://hutchdatascience.org/Intro_to_R/index.html#class-schedule

Ask Me Two Questions

What is a computer program?

  • A sequence of instructions to manipulate data for the computer to execute.
  • A series of translations: English <-> Programming Code for Interpreter <-> Machine Code for Central Processing Unit (CPU)

We will focus on English <-> Programming Code for R Interpreter in this class.

Another way of putting it: How we organize ideas <-> Instructing a computer to do something.

Posit Cloud tour and trying out your first analysis!

Break

A pre-course survey:

https://forms.gle/Hr59ZbAan1JTumCa7

Grammar Structure 1: Evaluation of Expressions

  • Expressions are built out of operations or functions.
  • Operations and functions take in data types and return another data type.
  • We can combine multiple expressions together to form more complex expressions: an expression can have other expressions nested inside it.

Examples

18 + 21
[1] 39
max(18, 21)
[1] 21
max(18 + 21, 65)
[1] 65
18 + (21 + 65)
[1] 104
nchar("ATCG")
[1] 4

Function machine from algebra class

Function machine from algebra class.

Operations are functions. We could have written:

sum(18, 21)
[1] 39
sum(18, sum(21, 65))
[1] 104

Data types

  • Numeric: 18, -21, 65, 1.25

  • Character: “ATCG”, “Whatever”, “948-293-0000”

  • Logical: TRUE, FALSE

Grammar Structure 2: Storing data types in the environment

To build up a computer program, we need to store our returned data type from our expression somewhere for downstream use.

x = 18 + 21

Execution rule for variable assignment

Evaluate the expression to the right of =.

Bind variable to the left of = to the resulting value.

The variable is stored in the environment.

<- is okay too!

Remember: Case (capitalization) Matters!

x is not equal to X

(If you’re coming from SAS)

Downstream

Look, now x can be reused downstream:

x - 2
[1] 37
y = x * 2
y
[1] 78

Grammar Structure 3: Evaluation of Functions

A function has a function name, arguments, and returns a data type.

Execution rule for functions:

Evaluate the function by its arguments, and if the arguments contain expressions, evaluate those expressions first.

The output of functions is called the returned value.

sqrt(nchar("hello"))
[1] 2.236068
(nchar("hello") + 4) * 2
[1] 18

A programming language has following features:

  • Grammar structure to construct expressions
  • Combining expressions to create more complex expressions
  • Encapsulate complex expressions via functions to create modular and reusable tasks
  • Encapsulate complex data via data structures to allow efficient manipulation of data

Tips on writing your first code

Computer = powerful + stupid

Even the smallest spelling and formatting changes will cause unexpected output and errors!

  • Write incrementally, test often
  • Check your assumptions, especially using new functions, operations, and new data types.
  • Live environments are great for testing, but not great for reproducibility.
  • Ask for help!

Taking the Temperature

Please take our weekly check in survey: https://forms.gle/vGMcWC5hZN3AcYYW8

  • Clearest Point
  • Muddiest Points: example here
  • Anything else you want to share

We will have a brief discussion before we start each class and respones will also be posted on the course website.

In Summary

  • We will use Posit Cloud for the course
  • Notebooks help you keep track of your work
  • Computers evaluate expressions, store variables, and use functions to do things
  • All materials will be posted here: https://hutchdatascience.org/Intro_to_R
  • Friday 10 - 11 am PT to practice together!