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Data Structures

Vectors

Vectors are defined as a sequence of data elements of a certain data type. Below are 3 different types of vectors as examples

Numeric Vectors

Num_Vec <- c(3,6,9)

[1] 3.2 6.0 9.0

Logical Vectors

Log_Vec <- c(“TRUE”, “TRUE”, “FALSE”)

[1] "TRUE"  "TRUE"  "FALSE"

Character Vectors

Char_Vec <- c(“Steve”, “Sarah”, “Tim”)

[1] "Steve" "Sarah" "Tim"  

Data Frames

A data frame is a named list of vectors where the length of each vector is must be the same.

df <- data.frame(Num_Vec, Log_Vec, Char_Vec)

##   Num_Vec Log_Vec Char_Vec
## 1       3    TRUE    Steve
## 2       6    TRUE    Sarah
## 3       9   FALSE      Tim

List

A list is a vector of data structures

mylist <- list(Num = Num_Vec,
Logic = Log_Vec,
Char = Char_Vec)

## $Num
## [1] 3 6 9
## 
## $Logic
## [1] "TRUE"  "TRUE"  "FALSE"
## 
## $Char
## [1] "Steve" "Sarah" "Tim"

Matrix

Matrix is two-dimensional data structures where all data types must be the same.

Below is an example of a matrix where we set the number of data elements to 20 where we have 5 columns each with 4 rows of data.

mat <- matrix(1:20, 4,5)

##      [,1] [,2] [,3] [,4] [,5]
## [1,]    1    5    9   13   17
## [2,]    2    6   10   14   18
## [3,]    3    7   11   15   19
## [4,]    4    8   12   16   20