# GroupedDataFrame combine unique non-key values
**URL:** https://discourse.julialang.org/t/groupeddataframe-combine-unique-non-key-values/51232
**Category:** General Usage
**Tags:** question, dataframes
**Created:** [December 4, 2020, 12:58am UTC](https://discourse.julialang.org/t/groupeddataframe-combine-unique-non-key-values/51232 "2020-12-04T00:58:58Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@mkarikom](https://discourse.julialang.org/u/mkarikom)
#### Post date: [December 4, 2020, 12:58am UTC](https://discourse.julialang.org/t/groupeddataframe-combine-unique-non-key-values/51232/1 "2020-12-04T00:58:58Z")
I have the following dataframe and I need to concatenate all unique values of `:c`
```julia
check = DataFrame(a=[1,2,2],b=["a","b","b"],c=[0,1,0])
check2 = check |> @groupby([:a,:b]) |> @combine(vcat=>:c=>:ccat)
@test check2 == DataFrame(a=[1,2],b=["a","b"],c=[[0],[1,0]])
```
---
### Author:  [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)
#### Post date: [December 4, 2020, 4:48am UTC](https://discourse.julialang.org/t/groupeddataframe-combine-unique-non-key-values/51232/2 "2020-12-04T04:48:21Z")
There is no `@groupby` macro. .
I guess you want the following?
```julia
julia> combine(groupby(check, [:a, :b]), :c => Ref ∘ unique => :ccat)
2×3 DataFrame
Row │ a b ccat
│ Int64 String Array…
─────┼───────────────────────
1 │ 1 a [0]
2 │ 2 b [1, 0]
```
---
### Author:  [@mkarikom](https://discourse.julialang.org/u/mkarikom)
#### Post date: [December 4, 2020, 6:30am UTC](https://discourse.julialang.org/t/groupeddataframe-combine-unique-non-key-values/51232/3 "2020-12-04T06:30:58Z")
awesome, thanks!