R Vectors

What Is a Vector?

A vector is an ordered collection of values that all share the same type - all numbers, all text, or all logical values. You build one with the c() function, short for combine. Vectors are the default shape of data in R: even a single number like 7 is technically a vector of length one.

scores <- c(88, 92, 76, 95, 60)
scores

fruits <- c("apple", "pear", "fig")
fruits

length(scores)

Giving Vector Elements Names

You can attach a name to each element of a vector, which makes it easier to read and lets you pull out values by label instead of position. Names are set inside c() or added afterward with the names() function.

inventory <- c(pens = 40, notebooks = 15, erasers = 22)
inventory

inventory["notebooks"]
names(inventory)

Indexing: Pulling Out Elements

R indexes vectors starting at 1, not 0. You can select elements by position, by a range, by name, or by a logical condition. Negative indices tell R to exclude an element rather than select it.

• scores[1] - the first element
• scores[2:4] - elements two through four
• scores[-1] - every element except the first
• scores[scores > 80] - every element that satisfies a condition
• inventory["pens"] - the element named "pens"

scores <- c(88, 92, 76, 95, 60)

scores[1]
scores[2:4]
scores[-1]
scores[scores > 80]