Statistics and Statistical Programming (Winter 2017)/R lecture outline: Week 1

Lecture Outline

Intro to R and basic variables types:

• using R as a calculator:
  • addition: 2 + 2
  • subtraction: 2 - 3
  • multiplication: 5 * 4
  • division: 5/2
  • more complicated stuff: use parentheses!
  • powers: 2^2; 2^3
• variables
  • the basic concept and how they work
  • syntax for assignment: use <- (although = equals too, it's not idiomatic R)
  • what makes a valid variables name: starts with a letter, contains letters and numbers; case is important; instead of spaces, use "." (not _ as in Python, although _ will usually work too)
  • saving numbers to variables: cups.of.flour <- 2
  • special variables built in: pi (we'll see many more)
• types of variables
  • numeric: we've already seen, with or without the decimal point
  • character: name <- "mako" (uses single or double quotes)
  • logical: TRUE or FALSE (all caps)
• functions: contains parens right after the variable name
  • there are many built in functions including:
    • sqrt()
    • log()
    • log1p() — super useful!
    • class() — tells you what type of variable you have
    • ls()
    • check your reference card for many, many more
• vectors: you can think of a vector as like a list of things that are all the same time (lists, which will come to letter, actually refer to lists of things that might be of different types!)
  • in R, all variables are vectors! although many have just one thing in them! that's why it prints out [1] next to every numbers
  • you can make vectors with a special function: c(), like ages <- c(36, 4, 35)
  • vectors can be of any type but they have to one type: c("mako", "mika")
  • if you mix vectors together, they will be "coerced"(!)
  • vectors can names for elements! we can set those with names():
    • names(ages)
    • names(ages) <- c("mako", "atom", "mika")
  • many functions are particularly useful on vectors with multiple elements:
    • sum()
    • mean()
    • median()
    • length()
    • head()
• installing new pacakges and loading new datasets:
  • install.packages("UsingR")
  • install.packages("openintro")
    • library(UsingR) no quotes!