 Supporting Statistical Analysis for Research

## 1.9 Vectorized functions

An R vector is a column of values. Each of the values of a vector have to be of the same type, number, character, etc. The values of a vector can be access based on the order of the values.

Many R functions parameters are vectors. Similarly, many operators operate on vectors. These functions and operators work on all the values of a column together. There are two common types of vector operations, transforming and aggregating. Aggregating is also know as summarizing.

Examples

1. Math with vectors

Adding two vectors is a transforming operation. The values of the two vectors are added element by element.

vec1 <- c(7, 5, 3, 1)
vec2 <- c(1, 2, 4, 8)

vec1 + vec2
 8 7 7 9

Multiplying works similarly.

vec1 * vec2
  7 10 12  8
2. Aggregating functions

The sum() function adds all the values of a vector together.

sum(vec1)
 16
sum(vec2)
 15
sum(vec1 * vec2)
 37
sum(vec1, vec2)
 31

Some other aggregating functions are, mean(), sd(), and median()

mean(vec1)
 4
median(vec2)
 3
mean(vec1 * vec2)
 9.25
sd(c(vec1, vec2))
 2.642374`