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I would like to create an empty vector and append to it an array in Julia. How do I do that?
x = Vector{Float64} append!(x, rand(10)) results in
`append!` has no method matching append!(::Type{Array{Float64,1}}, ::Array{Float64,1}) Thanks.
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Julia allows adding new elements in an array with the use of push! command. Elements in an array can also be added at a specific index by passing the range of index values in the splice! function.
"Appending" adds to the end of a list, "pushing" adds to the front.
A Vector in Julia can be created with the use of a pre-defined keyword Vector() or by simply writing Vector elements within square brackets([]). There are different ways of creating Vector. vector_name = [value1, value2, value3,..] or vector_name = Vector{Datatype}([value1, value2, value3,..])
Julia provides a very simple notation to create matrices. A matrix can be created using the following notation: A = [1 2 3; 4 5 6]. Spaces separate entries in a row and semicolons separate rows. We can also get the size of a matrix using size(A).
Your variable x does not contain an array but a type.
x = Vector{Float64} typeof(x) # DataType You can create an array as Array(Float64, n) (but beware, it is uninitialized: it contains arbitrary values) or zeros(Float64, n), where n is the desired size.
Since Float64 is the default, we can leave it out. Your example becomes:
x = zeros(0) append!( x, rand(10) ) I am somewhat new to Julia and came across this question after getting a similar error. To answer the original question for Julia version 1.2.0, all that is missing are ():
x = Vector{Float64}() append!(x, rand(10)) This solution (unlike x=zeros(0)) works for other data types, too. For example, to create an empty vector to store dictionaries use:
d = Vector{Dict}() push!(d, Dict("a"=>1, "b"=>2)) push! and append!:According to the Julia help, push! is used to add individual items to a collection, while append! adds an collection of items to a collection. So, the following pieces of code create the same array:
Push individual items:
a = Vector{Float64}() push!(a, 1.0) push!(a, 2.0) Append items contained in an array:
a = Vector{Float64}() append!(a, [1.0, 2.0]) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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