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

   [1] 8 7 7 9

   Multiplying works similarly.

   vec1 * vec2

   [1]  7 10 12  8

2. Aggregating functions

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

   sum(vec1)

   [1] 16

   sum(vec2)

   [1] 15

   sum(vec1 * vec2)

   [1] 37

   sum(vec1, vec2)

   [1] 31

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

   mean(vec1)

   [1] 4

   median(vec2)

   [1] 3

   mean(vec1 * vec2)

   [1] 9.25

   sd(c(vec1, vec2))

   [1] 2.642374