# Group, Mutate, Ungroup
**URL:** https://discourse.julialang.org/t/group-mutate-ungroup/8819
**Category:** Data
**Tags:** question, dataframes
**Created:** [February 4, 2018, 8:57pm UTC](https://discourse.julialang.org/t/group-mutate-ungroup/8819 "2018-02-04T20:57:28Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@RandomString123](https://discourse.julialang.org/u/RandomString123)
#### Post date: [February 4, 2018, 8:57pm UTC](https://discourse.julialang.org/t/group-mutate-ungroup/8819/1 "2018-02-04T20:57:28Z")
Is there a way developed to support the following workflow? I realize this example is trivial but it could be applied to more complex workflows like subgroup moving averages. And while there are ways to run calculations over a DataFrame in a way that does not need the following method sometimes it is easiest (mentally, temporally) to use this sort of brute force approach.
Goal: Number all rows in each group from 1:Number of Rows
Operation 1: Break DataFrame into SubGroups based on Attributes
Operation 2: Add column to each subgroup which numbers it from 1:Number of Rows
Operation 3: Ungroup SubGroups back into single DataFrame
I know Step1 is possible in Julia today. Is there a way to perform operations 2 and 3? I have tried to modify a SubDataFrame and it does not seem possible. Also I can’t find a way to ungroup a grouped dataFrame.
---
### Author:  [@nalimilan](https://discourse.julialang.org/u/nalimilan)
#### Post date: [February 4, 2018, 9:28pm UTC](https://discourse.julialang.org/t/group-mutate-ungroup/8819/2 "2018-02-04T21:28:56Z")
Does this suit your needs?
```julia
julia> df = DataFrame(x=[1, 1, 2, 2, 2, 3])
6×1 DataFrames.DataFrame
│ Row │ x │
├─────┼───┤
│ 1 │ 1 │
│ 2 │ 1 │
│ 3 │ 2 │
│ 4 │ 2 │
│ 5 │ 2 │
│ 6 │ 3 │
julia> by(df, :x) do sdf
DataFrame(n=1:size(sdf,1))
end
6×2 DataFrames.DataFrame
│ Row │ x │ n │
├─────┼───┼───┤
│ 1 │ 1 │ 1 │
│ 2 │ 1 │ 2 │
│ 3 │ 2 │ 1 │
│ 4 │ 2 │ 2 │
│ 5 │ 2 │ 3 │
│ 6 │ 3 │ 1 │
```
The `by` function is just a combination of `groupy` (operation 1) and `combine` (operation 3).
---
### Author:  [@RandomString123](https://discourse.julialang.org/u/RandomString123)
#### Post date: [February 4, 2018, 11:18pm UTC](https://discourse.julialang.org/t/group-mutate-ungroup/8819/3 "2018-02-04T23:18:35Z")
Sweet! I didn’t realize by…do could be used like that. I think because all of the examples did summary statistics I never thought to try it for non-summary methods.