# DataFrame transform with many output columns

**URL:** <https://discourse.julialang.org/t/dataframe-transform-with-many-output-columns/78593>\
**Category:** General Usage\
**Tags:** dataframes\
**Created:** [March 28, 2022, 8:48am UTC](https://discourse.julialang.org/t/dataframe-transform-with-many-output-columns/78593 "2022-03-28T08:48:05Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Mastomaki](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@Mastomaki](https://discourse.julialang.org/u/Mastomaki)\
**Post date:** [March 28, 2022, 8:48am UTC](https://discourse.julialang.org/t/dataframe-transform-with-many-output-columns/78593/1 "2022-03-28T08:48:05Z")

</div>

Hello!

I can split string columns in dataframe as follows:

```
s = DataFrame(grid = "uuu_mygrid", e = [3,3,3])
transform(s, :grid => (ByRow(x -> split(x,"_"))) => AsTable)

```

But how can I specify the new column names?

---

<div class="post-metadata">

**Author:** ![bkamins](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bkamins/32/208538_2.png) [@bkamins](https://discourse.julialang.org/u/bkamins)\
**Post date:** [March 28, 2022, 8:53am UTC](https://discourse.julialang.org/t/dataframe-transform-with-many-output-columns/78593/2 "2022-03-28T08:53:31Z")

</div>

just pass the column names you want:

```julia
julia> transform(s, :grid => (ByRow(x -> split(x,"_"))) => [:col1, :col2])
3×4 DataFrame
 Row │ grid e col1 col2
     │ String Int64 SubStrin… SubStrin…
─────┼─────────────────────────────────────────
   1 │ uuu_mygrid 3 uuu mygrid
   2 │ uuu_mygrid 3 uuu mygrid
   3 │ uuu_mygrid 3 uuu mygrid

```