Working with vectors/sequences

• The most fundamental data container in R is the vector, which is simply a finite sequence of elements of the same type.

• You can create a vector most simply using the c command, followed by a comma-separated list of values. For example: c(2, 5, 7), c("Blue", "Yellow", "Green")

• The seq command can be used to create a regular sequence of numbers. Try the following:

  seq(1, 10)
  seq(1, 10, by=0.1)
  seq(1, 10, length.out=30)

• You can use a colon between two integers to generate the sequence of integers from the first to the second, e.g. 17:15 will produce the sequence c(17, 16, 15)

• Printed vectors appear often in multiple lines, where the start of a line indicates in brackets the index for the first element in that line, starting from 1.

• You can find out the length of a vector using length:

  x <- seq(1, 10, by=0.1)
  length(x)    #  produces 91

• Operations on vectors happen element-wise:

  x <- 1:10
  y <- x + 5
  x
  y
  x + y
  x ^ 2
  2 ^ x