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Subsetting an NaArray object

NaArray-subsetting.Rd

EXPERIMENTAL!!!

Like ordinary arrays in base R, NaArray objects support subsetting via the single bracket operator ([).

See also

  • drop in base R to drop the ineffective dimensions of an array or array-like object.

  • Lindex2Mindex in the S4Arrays package for how to convert an L-index to an M-index and vice-versa.

  • NaArray objects.

  • [ and ordinary array objects in base R.

Examples

naa <- NaArray(dim=5:3)
naa[c(1:2, 8, 10, 15:17, 20, 24, 40, 56:60)] <- (1:15)*10L

## ---------------------------------------------------------------------
## N-dimensional subsetting
## ---------------------------------------------------------------------
naa[5:3, c(4,2,4), 2:3]
#> <3 x 3 x 2 NaArray> of type "integer" [nnacount=8 (44%)]:
#> ,,1
#>      [,1] [,2] [,3]
#> [1,]  100   NA  100
#> [2,]   NA   NA   NA
#> [3,]   NA   NA   NA
#> 
#> ,,2
#>      [,1] [,2] [,3]
#> [1,]  150   NA  150
#> [2,]  140   NA  140
#> [3,]  130   NA  130
#> 
naa[ , c(4,2,4), 2:3]
#> <5 x 3 x 2 NaArray> of type "integer" [nnacount=12 (40%)]:
#> ,,1
#>      [,1] [,2] [,3]
#> [1,]   NA   NA   NA
#> [2,]   NA   NA   NA
#> [3,]   NA   NA   NA
#> [4,]   NA   NA   NA
#> [5,]  100   NA  100
#> 
#> ,,2
#>      [,1] [,2] [,3]
#> [1,]  110   NA  110
#> [2,]  120   NA  120
#> [3,]  130   NA  130
#> [4,]  140   NA  140
#> [5,]  150   NA  150
#> 
naa[ , c(4,2,4), -1]
#> <5 x 3 x 2 NaArray> of type "integer" [nnacount=12 (40%)]:
#> ,,1
#>      [,1] [,2] [,3]
#> [1,]   NA   NA   NA
#> [2,]   NA   NA   NA
#> [3,]   NA   NA   NA
#> [4,]   NA   NA   NA
#> [5,]  100   NA  100
#> 
#> ,,2
#>      [,1] [,2] [,3]
#> [1,]  110   NA  110
#> [2,]  120   NA  120
#> [3,]  130   NA  130
#> [4,]  140   NA  140
#> [5,]  150   NA  150
#> 
naa[ , c(4,2,4), 1]
#> <5 x 3 NaMatrix> of type "integer" [nnacount=8 (53%)]:
#>      [,1] [,2] [,3]
#> [1,]   60   NA   60
#> [2,]   70   NA   70
#> [3,]   NA   30   NA
#> [4,]   NA   NA   NA
#> [5,]   80   40   80

naa2 <- naa[ , c(4,2,4), 1, drop=FALSE]
naa2
#> <5 x 3 x 1 NaArray> of type "integer" [nnacount=8 (53%)]:
#> ,,1
#>      [,1] [,2] [,3]
#> [1,]   60   NA   60
#> [2,]   70   NA   70
#> [3,]   NA   30   NA
#> [4,]   NA   NA   NA
#> [5,]   80   40   80
#> 

## Ineffective dimensions can always be dropped as a separate step:
drop(naa2)
#> <5 x 3 NaMatrix> of type "integer" [nnacount=8 (53%)]:
#>      [,1] [,2] [,3]
#> [1,]   60   NA   60
#> [2,]   70   NA   70
#> [3,]   NA   30   NA
#> [4,]   NA   NA   NA
#> [5,]   80   40   80

naa[ , c(4,2,4), integer(0)]
#> <5 x 3 x 0 NaArray> of type "integer" [nnacount=0 (NaN%)]

dimnames(naa) <- list(letters[1:5], NULL, LETTERS[1:3])

naa[c("d", "a"), c(4,2,4), "C"]
#> <2 x 3 NaMatrix> of type "integer" [nnacount=4 (67%)]:
#>   [,1] [,2] [,3]
#> d  140   NA  140
#> a  110   NA  110

naa2 <- naa["e", c(4,2,4), , drop=FALSE]
naa2
#> <1 x 3 x 3 NaArray> of type "integer" [nnacount=7 (78%)]:
#> ,,A
#>   [,1] [,2] [,3]
#> e   80   40   80
#> 
#> ,,B
#>   [,1] [,2] [,3]
#> e  100   NA  100
#> 
#> ,,C
#>   [,1] [,2] [,3]
#> e  150   NA  150
#> 

drop(naa2)
#> <3 x 3 NaMatrix> of type "integer" [nnacount=7 (78%)]:
#>        A   B   C
#> [1,]  80 100 150
#> [2,]  40  NA  NA
#> [3,]  80 100 150

## ---------------------------------------------------------------------
## 1D-style subsetting (a.k.a. linear subsetting)
## ---------------------------------------------------------------------

## Using a numeric vector (L-index):
naa[c(60, 24, 21, 56)]
#> [1] 150  90  NA 110

## Using a matrix subscript (M-index):
m <- rbind(c(5, 4, 3),
           c(4, 1, 2),
           c(1, 1, 2),
           c(1, 4, 3))
naa[m]
#> [1] 150  90  NA 110

## See '?Lindex2Mindex' in the S4Arrays package for how to convert an
## L-index to an M-index and vice-versa.

## ---------------------------------------------------------------------
## Sanity checks
## ---------------------------------------------------------------------
a <- as.array(naa)
naa2 <- naa[5:3, c(4,2,4), 2:3]
a2   <- a  [5:3, c(4,2,4), 2:3]
stopifnot(identical(as.array(naa2), a2), identical(naa2, NaArray(a2)))
naa2 <- naa[ , c(4,2,4), 2:3]
a2   <- a  [ , c(4,2,4), 2:3]
stopifnot(identical(as.array(naa2), a2), identical(naa2, NaArray(a2)))
naa2 <- naa[ , c(4,2,4), -1]
a2   <- a  [ , c(4,2,4), -1]
stopifnot(identical(as.array(naa2), a2), identical(naa2, NaArray(a2)))
naa2 <- naa[ , c(4,2,4), 1]
a2   <- a  [ , c(4,2,4), 1]
stopifnot(identical(as.array(naa2), a2), identical(naa2, NaArray(a2)))
naa2 <- naa[ , c(4,2,4), 1, drop=FALSE]
a2   <- a  [ , c(4,2,4), 1, drop=FALSE]
stopifnot(identical(as.array(naa2), a2), identical(naa2, NaArray(a2)))
naa2 <- drop(naa2)
a2 <- drop(a2)
stopifnot(identical(as.array(naa2), a2), identical(naa2, NaArray(a2)))
naa2 <- naa[ , c(4,2,4), integer(0)]
a2   <- a  [ , c(4,2,4), integer(0)]
stopifnot(identical(as.array(naa2), a2),
          identical(unname(naa2), unname(NaArray(a2))))
naa2 <- naa[c("d", "a"), c(4,2,4), "C"]
a2   <- a  [c("d", "a"), c(4,2,4), "C"]
stopifnot(identical(as.array(naa2), a2), identical(naa2, NaArray(a2)))
naa2 <- naa["e", c(4,2,4), , drop=FALSE]
a2   <- a  ["e", c(4,2,4), , drop=FALSE]
stopifnot(identical(as.array(naa2), a2), identical(naa2, NaArray(a2)))
naa2 <- drop(naa2)
a2 <- drop(a2)
stopifnot(identical(as.array(naa2), a2), identical(naa2, NaArray(a2)))
stopifnot(identical(naa[c(60, 24, 21, 56)], naa[m]))