10 Data Structures

Common Data Structures:

Vectors
- 1 Dimensional
- Homogenous data type
Matrices
- 2 Dimensional
- Homogenous data type
Arrays
- Greater than 2 Dimensions
- Homogenous data type
Data Frames
- 2 Dimensional
- Heterogenous data types
Lists
- Can contain various data types (vectors, matrices, arrays, and data frames)
- Heterogenous data types

10.1 Vectors

1 Dimensional
Homogenous data type

Numeric vector

c(1, 2, 3, 4, 5)

## [1] 1 2 3 4 5

Character Vector

c("A", "B", "C", "D", "E")

## [1] "A" "B" "C" "D" "E"

Logical vector

c(TRUE, FALSE, TRUE, FALSE, TRUE)

## [1]  TRUE FALSE  TRUE FALSE  TRUE

10.2 Matrices

2 Dimensional
Homogenous data type

matrix(c(1:5, 2, 7, 4, 9, 20, 40, 23, 64, 67, 80, 3, 76, 29, 59, 91),
       ncol = 4)

##      [,1] [,2] [,3] [,4]
## [1,]    1    2   40    3
## [2,]    2    7   23   76
## [3,]    3    4   64   29
## [4,]    4    9   67   59
## [5,]    5   20   80   91

10.3 Arrays

Greater than 2 Dimensions
Homogenous data type

array(c(c(1:5, 2, 7, 4, 9, 20, 40, 23, 64, 67, 80, 3, 76, 29, 59, 91, 1, 3, 5, 7, 9),
        c(2, 3, 34, 45, 57, 26, 74, 42, 91, 20, 1, 0, 82, 31, 45, 1, 0, 1, 0, 1, 9:5),
        c(1, 0, rep(1, 3), rep(0, 5), 1, 0, 1, 1, 0, rep(1, 5), 0, 0, 1, 1, 0)),
      c(5, 5, 3))

## , , 1
## 
##      [,1] [,2] [,3] [,4] [,5]
## [1,]    1    2   40    3    1
## [2,]    2    7   23   76    3
## [3,]    3    4   64   29    5
## [4,]    4    9   67   59    7
## [5,]    5   20   80   91    9
## 
## , , 2
## 
##      [,1] [,2] [,3] [,4] [,5]
## [1,]    2   26    1    1    9
## [2,]    3   74    0    0    8
## [3,]   34   42   82    1    7
## [4,]   45   91   31    0    6
## [5,]   57   20   45    1    5
## 
## , , 3
## 
##      [,1] [,2] [,3] [,4] [,5]
## [1,]    1    0    1    1    0
## [2,]    0    0    0    1    0
## [3,]    1    0    1    1    1
## [4,]    1    0    1    1    1
## [5,]    1    0    0    1    0

10.4 Data Frames

2 Dimensional
Heterogenous data types

data.frame(
  Numeric = c(1, 2, 3, 4, 5),
  Charcter = c("A", "B", "C", "D", "E"),
  Logical = c(TRUE, FALSE, TRUE, FALSE, TRUE),
  stringsAsFactors = FALSE
)

##   Numeric Charcter Logical
## 1       1        A    TRUE
## 2       2        B   FALSE
## 3       3        C    TRUE
## 4       4        D   FALSE
## 5       5        E    TRUE

10.5 Lists

Can contain various data types (Vectors, Matrices, Arrays, and Data Frames)
Heterogenous data types

list(
  c(TRUE, FALSE, TRUE, FALSE, TRUE),
  matrix(c("A", "B", "C", "D", "E",
           "AB", "BC", "CD", "DE", "EF",
           rep("BLAH", 5),
           "TEXT", "text", "TEXT", "text", "TEXT"),
         ncol = 4),
  array(c(c(1:5, 2, 7, 4, 9, 20, 40, 23, 64, 67, 80, 3, 76, 29, 59, 91, 1, 3, 5, 7, 9),
        c(2, 3, 34, 45, 57, 26, 74, 42, 91, 20, 1, 0, 82, 31, 45, 1, 0, 1, 0, 1, 9:5),
        c(1, 0, rep(1, 3), rep(0, 5), 1, 0, 1, 1, 0, rep(1, 5), 0, 0, 1, 1, 0)),
      c(5, 5, 3)),
  data.frame(
    Numeric = c(1, 2, 3, 4, 5),
    Charcter = c("A", "B", "C", "D", "E"),
    Logical = c(TRUE, FALSE, TRUE, FALSE, TRUE),
    stringsAsFactors = FALSE
  )
)

## [[1]]
## [1]  TRUE FALSE  TRUE FALSE  TRUE
## 
## [[2]]
##      [,1] [,2] [,3]   [,4]  
## [1,] "A"  "AB" "BLAH" "TEXT"
## [2,] "B"  "BC" "BLAH" "text"
## [3,] "C"  "CD" "BLAH" "TEXT"
## [4,] "D"  "DE" "BLAH" "text"
## [5,] "E"  "EF" "BLAH" "TEXT"
## 
## [[3]]
## , , 1
## 
##      [,1] [,2] [,3] [,4] [,5]
## [1,]    1    2   40    3    1
## [2,]    2    7   23   76    3
## [3,]    3    4   64   29    5
## [4,]    4    9   67   59    7
## [5,]    5   20   80   91    9
## 
## , , 2
## 
##      [,1] [,2] [,3] [,4] [,5]
## [1,]    2   26    1    1    9
## [2,]    3   74    0    0    8
## [3,]   34   42   82    1    7
## [4,]   45   91   31    0    6
## [5,]   57   20   45    1    5
## 
## , , 3
## 
##      [,1] [,2] [,3] [,4] [,5]
## [1,]    1    0    1    1    0
## [2,]    0    0    0    1    0
## [3,]    1    0    1    1    1
## [4,]    1    0    1    1    1
## [5,]    1    0    0    1    0
## 
## 
## [[4]]
##   Numeric Charcter Logical
## 1       1        A    TRUE
## 2       2        B   FALSE
## 3       3        C    TRUE
## 4       4        D   FALSE
## 5       5        E    TRUE