# Allowing a preexisting vector to contain missings later on

**URL:** <https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704>\
**Category:** New to Julia\
**Created:** [February 21, 2021, 12:56am UTC](https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704 "2021-02-21T00:56:14Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![askvorts](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/askvorts/32/7120_2.png) [@askvorts](https://discourse.julialang.org/u/askvorts)\
**Post date:** [February 21, 2021, 12:56am UTC](https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704/1 "2021-02-21T00:56:14Z")

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Following

```julia
A = [1.0, 2.0]
A = Union{Float64,Missing}[1.0, 2.0]
A[1] = missing # Union{Missing, Float64}[missing, 2.0]

```

tried

```julia
B = [1.0, 2.0]
missB = Union{Float64,Missing}B # errors

```

How may I accomplish this? Thank you in advance.

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**Author:** ![jling](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jling/32/212909_2.png) [@jling](https://discourse.julialang.org/u/jling)\
**Post date:** [February 21, 2021, 1:04am UTC](https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704/2 "2021-02-21T01:04:30Z")

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```julia
Array{Union{Float64,Missing}}(B)

```

the syntax of `T[1,2,3]` works because `getindex(T, 1,2,3)` is understood (specially) as making a vector of element type `T`. The `TB` is understood to be `T*B` which doesn’t make sense.

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**Author:** ![askvorts](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/askvorts/32/7120_2.png) [@askvorts](https://discourse.julialang.org/u/askvorts)\
**Post date:** [February 21, 2021, 1:22am UTC](https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704/3 "2021-02-21T01:22:19Z")

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@jling thank you for your reply. Now I am getting `ERROR: LoadError: MethodError: no method matching Union{Missing, Float64}(::Vector{Float64})`

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**Author:** ![jling](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jling/32/212909_2.png) [@jling](https://discourse.julialang.org/u/jling)\
**Post date:** [February 21, 2021, 1:26am UTC](https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704/4 "2021-02-21T01:26:39Z")

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can you post complete code?

you forgot the `Array`?

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<div class="post-metadata">

**Author:** ![askvorts](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/askvorts/32/7120_2.png) [@askvorts](https://discourse.julialang.org/u/askvorts)\
**Post date:** [February 21, 2021, 1:28am UTC](https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704/5 "2021-02-21T01:28:24Z")

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Yes, I forgot it! Thank you very much for your help

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**Author:** ![pdeffebach](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pdeffebach/32/10320_2.png) [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Post date:** [February 21, 2021, 1:47am UTC](https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704/6 "2021-02-21T01:47:25Z")

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You can also use `allowmissing(v)`

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<div class="post-metadata">

**Author:** ![jling](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jling/32/212909_2.png) [@jling](https://discourse.julialang.org/u/jling)\
**Post date:** [February 21, 2021, 2:00am UTC](https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704/7 "2021-02-21T02:00:06Z")

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> [@pdeffebach](#):
>
> `allowmissing`

isn’t that from like DataFrame?

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**Author:** ![pdeffebach](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pdeffebach/32/10320_2.png) [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Post date:** [February 21, 2021, 2:01am UTC](https://discourse.julialang.org/t/allowing-a-preexisting-vector-to-contain-missings-later-on/55704/8 "2021-02-21T02:01:27Z")

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Yes but its defined for arrays as well in Missings.jl (I didn’t realize it was in Missings earlier)