Reshape an array

Pipe friendly dim<-(), with option to pad to necessary length. Also allows for filling the array using C style row-major semantics.

set_dim(
  x,
  new_dim,
  pad = getOption("listarrays.autopad_arrays_with", NULL),
  order = c("F", "C"),
  verbose = getOption("verbose")
)

Arguments

x	A vector or array to set dimensions on
new_dim	The desired dimensions (an integer(ish) vector)
pad	The value to pad the vector with. NULL (the default) performs no padding.
order	whether to use row-major (C) or column major (F) style semantics. The default, "F", corresponds to the default behavior of R's dim<-(), while "C" corresponds to the default behavior of reticulate::array_reshape(), numpy, reshaping semantics commonly encountered in the python world.
verbose	Whether to emit a message if padding. By default, FALSE.

Value

Object with dimensions set

See also

set_dim2(), `dim<-`(), reticulate::array_reshape()

Examples

set_dim(1:10, c(2, 5))
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    1    3    5    7    9
#> [2,]    2    4    6    8   10
try( set_dim(1:7, c(2, 5)) ) # error by default, just like `dim<-`()
#> Error in dim(x) <- new_dim : 
#>   dims [product 10] do not match the length of object [7]
     set_dim(1:7, c(2, 5), pad = 99)
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    1    3    5    7   99
#> [2,]    2    4    6   99   99
     set_dim(1:7, c(2, 5), pad = 99, order = "C") # fills row-wise
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    1    2    3    4    5
#> [2,]    6    7   99   99   99

y <- x <- 1:4
# base::dim<- fills the array column wise
dim(x) <- c(2, 2)
x
#>      [,1] [,2]
#> [1,]    1    3
#> [2,]    2    4

# dim2 will fill the array row-wise
dim2(y) <- c(2, 2)
y
#>      [,1] [,2]
#> [1,]    1    2
#> [2,]    3    4

identical(x, set_dim(1:4, c(2,2)))
#> [1] TRUE
identical(y, set_dim(1:4, c(2,2), order = "C"))
#> [1] TRUE

if (FALSE) {
py_reshaped <- reticulate::array_reshape(1:4, c(2,2))
storage.mode(py_reshaped) <- "integer" # reticulate coerces to double
identical(y, py_reshaped)
# if needed, see listarrays:::array_reshape() for
# a drop-in pure R replacement for reticulate::array_reshape()
}