ConstantArray{T,D} <: AbstractArray{T,D}

• value::T
• dim::Dims{D}

ConstantArray(value, dim::Dims)
ConstantArray(dim::Dims) (default value=1)

Return a read-only AbstractArray of dimension dim as if it is filled with the constant value, i.e., equivalent to fill(value, dim) except it uses much less memory.

The setindex! operation is not allowed for ConstantArray

Examples

julia> x = ConstantArray(7, (2,3))
2×3 ConstantArray{Int64,2}:
 7  7  7
 7  7  7

julia> x[1]
7

julia> x[1] = 10
ERROR: setindex! not defined for ConstantArray{Int64,2}
[...]

getindex(x::AbstractArray{T,D}, mask::ConstantArray{Bool,D})

Ensure that x[mask] is efficient.

show(io::IO, x::ConstantArray)
show(io::IO, ::MIME"text/plain", x::ConstantArray)

Concise description.

getindex!(y::AbstractVector, x::AbstractArray{T,D}, mask::ConstantArray{Bool,D})

Equivalent to the in-place y .= x[mask] but is non-allocating.

For non-Boolean indexing, just use @views y .= A[index], per https://discourse.julialang.org/t/efficient-non-allocating-in-place-getindex-for-bitarray/42268