# @replacena not working with variables as replacement value
**URL:** https://discourse.julialang.org/t/replacena-not-working-with-variables-as-replacement-value/45401
**Category:** New to Julia
**Tags:** query
**Created:** [August 23, 2020, 4:09am UTC](https://discourse.julialang.org/t/replacena-not-working-with-variables-as-replacement-value/45401 "2020-08-23T04:09:59Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@TheRoniOne](https://discourse.julialang.org/u/TheRoniOne)
#### Post date: [August 23, 2020, 4:09am UTC](https://discourse.julialang.org/t/replacena-not-working-with-variables-as-replacement-value/45401/1 "2020-08-23T04:09:59Z")
Hi, was trying to practice some simple data cleaning with Query.jl modifying a bit an example of the documentation.
What I intended to do was to replace all the missing values in a column with the mean of that column.
> using Queryverse
> using Statistics
>
> df = DataFrame(a=[1,2,missing], b=[“One”,missing,“Three”])
> myMean = mean(skipmissing(df.a))
> q = df |\> @replacena(:b=\>“Unknown”, :a=\>myMean) |\> DataFrame
Wich trigered an error.
> julia\> q = df |\> @replacena(:b=\>“Unknown”, :a=\>myMean) |\> DataFrame
> ERROR: UndefVarError: myMean not defined
So I decided to try using another function of Query to see if it was expected to work that way.
> julia\> df |\> @mutate(c = myMean)
> 3x3 query result
> a │ b │ c
> ────┼─────────┼────
> 1 │ “One” │ 1.5
> 2 │ #NA │ 1.5
> #NA │ “Three” │ 1.5
And it did.
Finally, decided to try without using a variable and just using the function that returns the value wich I was trying to use to replace missing values with.
> q = df |\> @replacena(:b=\>“Unknown”, :a=\>mean(skipmissing(\_.a))) |\> DataFrame
Still got an error.
> julia\> q = df |\> @replacena(:b=\>“Unknown”, :a=\>mean(skipmissing(\_.a))) |\> DataFrame
> ERROR: UndefVarError: mean not defined
Any help will be apreciated.
---
### Author:  [@oheil](https://discourse.julialang.org/u/oheil)
#### Post date: [August 23, 2020, 9:19am UTC](https://discourse.julialang.org/t/replacena-not-working-with-variables-as-replacement-value/45401/2 "2020-08-23T09:19:14Z")
I can only guess, despite your fine MWE but Queryverse doesn’t compile in my environment (python36.dll missing).
The docs
[https://www.queryverse.org/Query.jl/stable/standalonequerycommands/#The-@replacena-command-1](https://www.queryverse.org/Query.jl/stable/standalonequerycommands/#The-@replacena-command-1)
aren’t explicit but talk only about values. So my guess is that
`q = df |> @replacena(:b=>"Unknown", :a=> $myMean ) |> DataFrame`
could do.
[https://docs.julialang.org/en/v1/manual/metaprogramming/#man-expression-interpolation-1](https://docs.julialang.org/en/v1/manual/metaprogramming/#man-expression-interpolation-1)
---
### Author:  [@TheRoniOne](https://discourse.julialang.org/u/TheRoniOne)
#### Post date: [August 23, 2020, 4:43pm UTC](https://discourse.julialang.org/t/replacena-not-working-with-variables-as-replacement-value/45401/3 "2020-08-23T16:43:40Z")
Tried with
`julia> q = df |> @replacena(:b=>"Unknown", :a=> $myMean ) |> DataFrame`
Got
`ERROR: syntax: "$" expression outside quote around C:\Users\RoniD\.julia\packages\Query\85Sw7\src\query_translation.jl:58`
Also tried with
`julia> q = df |> @replacena(:b=>"Unknown", :a=> "$myMean") |> DataFrame`
And got another error
`ERROR: UndefVarError: myMean not defined`
---
### Author:  [@oheil](https://discourse.julialang.org/u/oheil)
#### Post date: [August 23, 2020, 5:09pm UTC](https://discourse.julialang.org/t/replacena-not-working-with-variables-as-replacement-value/45401/4 "2020-08-23T17:09:10Z")
Ok, I had to remove my .julia to get a working Queryverse#master. This is the working syntax:
```julia
julia> using DataFrames, Queryverse, Statistics
julia> df = DataFrame(a=[1,2,missing], b=["One",missing,"Three"])
3×2 DataFrame
│ Row │ a │ b │
│ │ Int64? │ String? │
├─────┼─────────┼─────────┤
│ 1 │ 1 │ One │
│ 2 │ 2 │ missing │
│ 3 │ missing │ Three │
julia> myMean = mean(skipmissing(df.a))
1.5
julia> q = df |> @replacena(:b=>"Unknown", :a => :( $myMean ) ) |> DataFrame
3×2 DataFrame
│ Row │ a │ b │
│ │ Any │ Any │
├─────┼─────┼─────────┤
│ 1 │ 1 │ One │
│ 2 │ 2 │ Unknown │
│ 3 │ 1.5 │ Three │
```
---
### Author:  [@TheRoniOne](https://discourse.julialang.org/u/TheRoniOne)
#### Post date: [August 23, 2020, 5:18pm UTC](https://discourse.julialang.org/t/replacena-not-working-with-variables-as-replacement-value/45401/5 "2020-08-23T17:18:25Z")
Thanks!
It does work now.