# Summing over missing column values in a DataFrame

**URL:** <https://discourse.julialang.org/t/summing-over-missing-column-values-in-a-dataframe/64547>\
**Category:** General Usage\
**Tags:** dataframes\
**Created:** [July 13, 2021, 1:14am UTC](https://discourse.julialang.org/t/summing-over-missing-column-values-in-a-dataframe/64547 "2021-07-13T01:14:59Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ismam](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ismam/32/26140_2.png) [@Ismam](https://discourse.julialang.org/u/Ismam)\
**Post date:** [July 13, 2021, 1:15am UTC](https://discourse.julialang.org/t/summing-over-missing-column-values-in-a-dataframe/64547/1 "2021-07-13T01:15:00Z")

</div>

Hi, I’m using DataFramesMeta and having trouble with wrangling with missing values.

`df = DataFrame(x = 1:5, y = [missing, 4, missing, 2, 1])`

| | x | y |
| --- | --- | --- |
| | Int64 | Int64? |
| 1 | 1 | missing |
| 2 | 2 | 4 |
| 3 | 3 | missing |
| 4 | 4 | 2 |
| 5 | 5 | 1 |

I want to create a new column that sums over x and y.

`df2 = @transform(df, z = sum(skipmissing([:x, :y])))`

I thought the skipmissing feature would help out here, but struggling to make it work. Any tips?

---

<div class="post-metadata">

**Author:** ![pdeffebach](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pdeffebach/32/10320_2.png) [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Post date:** [July 13, 2021, 1:26am UTC](https://discourse.julialang.org/t/summing-over-missing-column-values-in-a-dataframe/64547/2 "2021-07-13T01:26:27Z")

</div>

Do you need to do this by row? Like add `:x` and `:y` from each row?

On more recent versions, you can do

```julia
@transform df @byrow y = sum(skipmissing([:x, :y]))

```

---

<div class="post-metadata">

**Author:** ![xiaodai](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xiaodai/32/15937_2.png) [@xiaodai](https://discourse.julialang.org/u/xiaodai)\
**Post date:** [July 13, 2021, 3:39am UTC](https://discourse.julialang.org/t/summing-over-missing-column-values-in-a-dataframe/64547/3 "2021-07-13T03:39:03Z")

</div>

> [@Ismam](#):
>
> sums over x and y.

what’s your expected output?

```julia
using Chain, DataFrameMacros
@chain df begin
  @transform :z = @m :x + :y
end

@chain df begin
  @transform :z = sum(skipmissing([:x, :y]))
end

```