4. Arrays

#An array with one dimension with values ranging from 1 to 36
arr_number <- c(1:36)
arr_number

##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
## [26] 26 27 28 29 30 31 32 33 34 35 36

#An array with more than one dimension

arr_multi <- array(arr_number, dim = c(6, 3, 2))
arr_multi

## , , 1
## 
##      [,1] [,2] [,3]
## [1,]    1    7   13
## [2,]    2    8   14
## [3,]    3    9   15
## [4,]    4   10   16
## [5,]    5   11   17
## [6,]    6   12   18
## 
## , , 2
## 
##      [,1] [,2] [,3]
## [1,]   19   25   31
## [2,]   20   26   32
## [3,]   21   27   33
## [4,]   22   28   34
## [5,]   23   29   35
## [6,]   24   30   36

#Array length
length(arr_multi)

## [1] 36

#Access array items
#array [row position, column position, matrix level]

arr_multi[6, 3, 2]

## [1] 36

arr_multi[c(1,3), 2, 2]

## [1] 25 27

arr_multi[, -c(2), 2]

##      [,1] [,2]
## [1,]   19   31
## [2,]   20   32
## [3,]   21   33
## [4,]   22   34
## [5,]   23   35
## [6,]   24   36

#Check if an item exists

if(32 %in% arr_multi){
  print("TRUE")
}else{
  print("FALSE")
}

## [1] "TRUE"

#Loop through an Array
for(i in arr_multi){
  cat("The number is: ", i, "\n")
}

## The number is:  1 
## The number is:  2 
## The number is:  3 
## The number is:  4 
## The number is:  5 
## The number is:  6 
## The number is:  7 
## The number is:  8 
## The number is:  9 
## The number is:  10 
## The number is:  11 
## The number is:  12 
## The number is:  13 
## The number is:  14 
## The number is:  15 
## The number is:  16 
## The number is:  17 
## The number is:  18 
## The number is:  19 
## The number is:  20 
## The number is:  21 
## The number is:  22 
## The number is:  23 
## The number is:  24 
## The number is:  25 
## The number is:  26 
## The number is:  27 
## The number is:  28 
## The number is:  29 
## The number is:  30 
## The number is:  31 
## The number is:  32 
## The number is:  33 
## The number is:  34 
## The number is:  35 
## The number is:  36