fill!(A, x)

Fill array A with the value x. If x is an object reference, all elements will refer to the same object. fill!(A, Foo()) will return A filled with the result of evaluating Foo() once.


julia> foo = Array(Int8,1,2);
julia> fill!(foo, 42)
1x2 Array{Int8,2}:
 42     42

Referencing another collection

 julia> foo = [1,2];
 julia> bar = Array(Any,1);
 julia> fill!(bar,foo)
 1-element Array{Any,1}:
 julia> foo[1] = 42;
 julia> bar
 1-element Array{Any,1}:

Using functions

julia> function Foo()
julia> bar = Array(Int8,2);
julia> fill!(bar, Foo())
2-element Array{Int64,1}:
  1. Fill an array with a specific value:

    julia> arr = [0, 0, 0, 0, 0];
    julia> fill!(arr, 5)
    5-element Array{Int64,1}:

    This example fills the array arr with the value 5.

  2. Fill a matrix with a specific value:

    julia> matrix = zeros(3, 3);
    julia> fill!(matrix, 1.5)
    3×3 Array{Float64,2}:
    1.5  1.5  1.5
    1.5  1.5  1.5
    1.5  1.5  1.5

    It fills a matrix of zeros with the value 1.5.

  3. Fill an array with a complex number:

    julia> complex_arr = Vector{ComplexF64}(undef, 4);
    julia> fill!(complex_arr, 1 + 2im)
    4-element Array{ComplexF64,1}:
    1.0 + 2.0im
    1.0 + 2.0im
    1.0 + 2.0im
    1.0 + 2.0im

    In this example, it fills an array with complex numbers.

  4. Fill an array with a custom object:
    julia> struct Person
    julia> people = Vector{Person}(undef, 3);
    julia> fill!(people, Person("John", 25))
    3-element Array{Person,1}:
    Person("John", 25)
    Person("John", 25)
    Person("John", 25)

    The fill! function can also be used to fill an array with custom objects. In this case, it fills an array with instances of the Person struct.

Common mistake example:

julia> arr = [1, 2, 3, 4, 5];
julia> fill!(arr, 1:3)
ERROR: DimensionMismatch("tried to assign 3 elements to 5 destinations")

In this example, an error occurs because the size of the value being filled (1:3) does not match the size of the array (arr). Make sure the dimensions match to avoid such errors when using fill!.

See Also

Array, broadcast, cat, combinations, conj!, digits!, fieldnames, fill, fill!, last, length, maximum, minimum, ones, parent, parentindexes, partitions, permutations, pointer, pointer_to_array, promote_shape, rand!, reshape, scale, similar, sum, sum_kbn, takebuf_array, transpose!, vec, zeros,

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