# Combining strings

**URL:** <https://discourse.julialang.org/t/combining-strings/44007>\
**Category:** New to Julia\
**Created:** [July 30, 2020, 8:58pm UTC](https://discourse.julialang.org/t/combining-strings/44007 "2020-07-30T20:58:46Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![bsmith](https://avatars.discourse-cdn.com/v4/letter/b/7feea3/32.png) [@bsmith](https://discourse.julialang.org/u/bsmith)\
**Post date:** [July 30, 2020, 8:58pm UTC](https://discourse.julialang.org/t/combining-strings/44007/1 "2020-07-30T20:58:46Z")

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Hi,

I am trying to process some string data - each element of the array should be split up into individual words and then combined. At the end, I only want the unique words in the array. In R, I would just run a loop and use c() to add to the array at each iteration. My code is:

```julia
mystrs = ["SWT1;SWT1;LPT","ABC;ABC| LPT; NYP","ABCD ;ABC|PT; NYP"]

function fsep(tstr,splits = (';','|',','))
    tstr2 = split(tstr,splits)
    tstr3 = sort(unique(map(strip,tstr2)))
    return tstr3
end

myset = []
for i = 1:3
    tgenes = fsep(mystrs[i])
    push!(myset,tgenes)
end

uset = unique(myset)

```

The output is:

```julia
julia> uset
3-element Array{Any,1}:
 SubString{String}["LPT", "SWT1"]
 SubString{String}["ABC", "LPT", "NYP"]
 SubString{String}["ABC", "ABCD", "NYP", "PT"]

```

whereas, I want it to be [“ABC”,“ABCD”,“LPT”,“NYP”,“PT”]

What would be the best structure and code to do this?

many thanks for your help!

PS: Any other observations/suggestions on code would be very welcome. Good to learn!!

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<div class="post-metadata">

**Author:** ![tomerarnon](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tomerarnon/32/3170_2.png) [@tomerarnon](https://discourse.julialang.org/u/tomerarnon)\
**Post date:** [July 30, 2020, 9:13pm UTC](https://discourse.julialang.org/t/combining-strings/44007/2 "2020-07-30T21:13:41Z")

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How about

```julia
julia> unique(mapreduce(x-> split(x, (';', '|', ' ')), vcat, mystrs))
7-element Array{SubString{String},1}:
 "SWT1"
 "LPT" 
 "ABC" 
 ""    
 "NYP" 
 "ABCD"
 "PT"  

```

If you have a much longer collection, and expect to see a lot of repetition in these substrings, you might choose to go with:

```julia
mapreduce(x -> Set(split(x, (';', '|', ' '))), union!, mystrs)

```

which performs the `unique` step each time (when it forms the Set) rather than once at the end.

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<div class="post-metadata">

**Author:** ![bsmith](https://avatars.discourse-cdn.com/v4/letter/b/7feea3/32.png) [@bsmith](https://discourse.julialang.org/u/bsmith)\
**Post date:** [July 30, 2020, 9:59pm UTC](https://discourse.julialang.org/t/combining-strings/44007/3 "2020-07-30T21:59:19Z")

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Thanks for the solution! The first version works great!

```julia
res1 = unique(mapreduce(x-> split(x, (';', '|',',')), vcat, mystrs))
res2 = sort(unique(map(strip,res1)))

```

I do have a very large collection with significant overlaps, so I am keen to implement the second solution too. I can do the first part and get a set, but it complains that map cannot be used in sets (to strip whitespace):

```julia
res3 = mapreduce(x -> Set(split(x, (';','|'))),union!, mystrs)
res4 = sort(map(strip,res3))

julia> res4 = sort(map(strip,res3))

ERROR: map is not defined on sets
Stacktrace:
 [1] error(::String) at ./error.jl:33
 [2] map(::Function, ::Set{SubString{String}}) at ./abstractarray.jl:2101
 [3] top-level scope at none:0

```

I tried to use Parse but get an error too:

```julia
julia> res3x = Parse(string,res3)
ERROR: UndefVarError: Parse not defined
Stacktrace:
 [1] top-level scope at none:0

```

How do I get the result from ‘set’ back again to ‘String’?

thanks a ton!

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<div class="post-metadata">

**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [July 31, 2020, 7:56am UTC](https://discourse.julialang.org/t/combining-strings/44007/4 "2020-07-31T07:56:40Z")

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> [@bsmith](#):
>
> I tried to use Parse but get an error too:

It is unclear what `Parse` is in this context. If you meant `Base.parse`, that’s for parsing numbers etc, so I am not sure how it applies here.

> [@bsmith](#):
>
> How do I get the result from ‘set’ back again to ‘String’?

You mean `Set` to `Vector`? Just use `collect`.

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<div class="post-metadata">

**Author:** ![tomerarnon](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tomerarnon/32/3170_2.png) [@tomerarnon](https://discourse.julialang.org/u/tomerarnon)\
**Post date:** [July 31, 2020, 10:53am UTC](https://discourse.julialang.org/t/combining-strings/44007/5 "2020-07-31T10:53:49Z")

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Note that since I was splitting also on the `' ' ` character (space), there is no need to call `strip` (which strips whitespace) at the end (you will simply end up with one member of the set that is an empty string `""`).  
That said, you can do strip without `map`.

```julia
julia> substrs = mapreduce(x -> Set(split(x, (';', '|', ' '))), union!, mystrs)
Set(SubString{String}["NYP", "ABCD", "PT", "LPT", "SWT1", "", "ABC"])

julia> strip.(substrs)
7-element Array{SubString{String},1}:
 "NYP" 
 "ABCD"
 "PT"  
 "LPT" 
 "SWT1"
 ""    
 "ABC" 

```

Note that sort also isn’t defined for sets, but you can turn a `Set` into an `Vector` with `collect`