# How to append to arrays in a dictionary one by one?

**URL:** <https://discourse.julialang.org/t/how-to-append-to-arrays-in-a-dictionary-one-by-one/12818>\
**Category:** General Usage\
**Tags:** question, array, dictionary, loops\
**Created:** [August 2, 2018, 10:33am UTC](https://discourse.julialang.org/t/how-to-append-to-arrays-in-a-dictionary-one-by-one/12818 "2018-08-02T10:33:51Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![wei](https://avatars.discourse-cdn.com/v4/letter/w/90ced4/32.png) [@wei](https://discourse.julialang.org/u/wei)\
**Post date:** [August 2, 2018, 10:33am UTC](https://discourse.julialang.org/t/how-to-append-to-arrays-in-a-dictionary-one-by-one/12818/1 "2018-08-02T10:33:52Z")

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Hello,  
I would like to append to arrays in a dict different items for each entry. What I coded simplified is:

entries = [“A”,“B”,“C”]  
entryvalues = fill(Float64,size(entries))  
dict = Dict(zip(entries, entryvalues))

which gives so far:

Dict{String,Array{Float64,1}} with 3 entries:  
“B” =\> Float64  
“A” =\> Float64  
“C” =\> Float64

Until here it’s fine. Then I would like to append different values to the different entryvalues. I tried:

i=1  
for x in dict  
append!(x[2],5\*i)  
println(x[1],x[2])  
i=i+1  
end

the output is:

B[5.0]  
A[5.0, 10.0]  
C[5.0, 10.0, 15.0]

and the whole dict now looks like  
“B” =\> [5.0, 10.0, 15.0]  
“A” =\> [5.0, 10.0, 15.0]  
“C” =\> [5.0, 10.0, 15.0]

what I was expecting for the final dict is something like  
“B” =\> [5.0]  
“A” =\> [10.0]  
“C” =\> [15.0]

so instead of only appending to the entryvalue of only “A”, only “B” or only “C” in the loop, it appends the value to all three entries. That appeared weird to me and I don’t know, how to fix this. Is there another way to code it or is it a bug in juliaLang?

Thank you,  
Wei

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<div class="post-metadata">

**Author:** ![fredrikekre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fredrikekre/32/1688_2.png) [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)\
**Post date:** [August 2, 2018, 10:39am UTC](https://discourse.julialang.org/t/how-to-append-to-arrays-in-a-dictionary-one-by-one/12818/2 "2018-08-02T10:39:06Z")

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> [@wei](#):
>
> entryvalues = fill(Float64,size(entries))

This fills a vector with the _same_ empty vector of `Float64`. If you want them all to be separate you can change this to

```julia
entryvalues = [Float64[] for _ in 1:length(entries)]

```

See also [PSA: how to quote code with backticks](https://discourse.julialang.org/t/psa-how-to-quote-code-with-backticks/7530) for formatting your code.

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**Author:** ![wei](https://avatars.discourse-cdn.com/v4/letter/w/90ced4/32.png) [@wei](https://discourse.julialang.org/u/wei)\
**Post date:** [August 2, 2018, 12:05pm UTC](https://discourse.julialang.org/t/how-to-append-to-arrays-in-a-dictionary-one-by-one/12818/3 "2018-08-02T12:05:31Z")

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Nice, that solves the problem!  
Thank you.