# Creating dataframe with column name that is a variable
**URL:** https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248
**Category:** General Usage
**Created:** [March 30, 2021, 4:30pm UTC](https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248 "2021-03-30T16:30:26Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@waforbes](https://discourse.julialang.org/u/waforbes)
#### Post date: [March 30, 2021, 4:30pm UTC](https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248/1 "2021-03-30T16:30:26Z")
All of the other columns are correct, i.e. I want “StartPoint” to be the name of the column and it has the data in the variable **start\_space**. Below, **param** is a string variable. How do I tell it that I want the column name to be the value of the string variable? For example, when **param** = “diffusion”, I want the column name to be “diffusion” based on the **param** variable.
speed\_df = DataFrame(StartPoint = start\_space, EndPoint = end\_space,
TimeInterval = time\_interval, DistanceInterval = distance\_interval,
Speed = speed, param = key)
---
### Author:  [@waforbes](https://discourse.julialang.org/u/waforbes)
#### Post date: [March 30, 2021, 4:34pm UTC](https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248/2 "2021-03-30T16:34:42Z")
Sorry, this is wrong. Given that it didn’t work above, I should have tried
speed\_df = rename!(speed\_df, :param =\> param).
**Edit: Below is wrong.**
I even tried
speed\_df = rename!(speed\_df, :param =\> key),
but it returned with
> LoadError: MethodError: no method matching rename!(::DataFrame, ::Vector{Pair{Symbol, Float64}})
>
> Closest candidates are:
>
> rename!(::AbstractDataFrame, !Matched::AbstractVector{Symbol}; makeunique) at /home/wesley/.julia/packages/DataFrames/zXEKU/src/abstractdataframe/abstractdataframe.jl:170
>
> rename!(::AbstractDataFrame, !Matched::AbstractVector{var"#s3"} where var"#s3"\<:AbstractString; makeunique) at /home/wesley/.julia/packages/DataFrames/zXEKU/src/abstractdataframe/abstractdataframe.jl:176
>
> rename!(::AbstractDataFrame, !Matched::AbstractVector{Pair{Symbol, Symbol}}) at /home/wesley/.julia/packages/DataFrames/zXEKU/src/abstractdataframe/abstractdataframe.jl:182
>
> …
>
> in expression starting at /home/wesley/repos/pde/juliatest.jl:149
>
> rename!(df::DataFrame, args::Pair{Symbol, Float64}) at abstractdataframe.jl:208
>
> calc\_speed(df::DataFrame, h::Float64, k::Float64, param::String, key::Float64) at juliatest.jl:86
>
> process(a::Int64, b::Int64, T::Int64, t\_steps::Int64, param::String, r\_start::Float64, r\_end::Int64, r\_length::Int64) at juliatest.jl:142
>
> top-level scope at juliatest.jl:149
>
> eval at boot.jl:360 [inlined]
>
> include\_string(mapexpr::typeof(identity), mod::Module, code::String, filename::String) at loading.jl:1094
---
### Author:  [@oheil](https://discourse.julialang.org/u/oheil)
#### Post date: [March 30, 2021, 4:42pm UTC](https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248/3 "2021-03-30T16:42:10Z")
I am not sure if I understand your question properly, but I try:
```julia
julia> using DataFrames
julia> df=DataFrame( A = [1,2,3] , B = [4,5,6] )
3×2 DataFrame
Row │ A B
│ Int64 Int64
─────┼──────────────
1 │ 1 4
2 │ 2 5
3 │ 3 6
julia> colname="X"
"X"
julia> rename!(df,:B => colname )
3×2 DataFrame
Row │ A X
│ Int64 Int64
─────┼──────────────
1 │ 1 4
2 │ 2 5
3 │ 3 6
```
Is this what you like to achieve?
---
### Author:  [@waforbes](https://discourse.julialang.org/u/waforbes)
#### Post date: [March 30, 2021, 4:46pm UTC](https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248/4 "2021-03-30T16:46:18Z")
Yes. You’ve understood correctly.
---
### Author:  [@rdeits](https://discourse.julialang.org/u/rdeits)
#### Post date: [March 30, 2021, 4:46pm UTC](https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248/5 "2021-03-30T16:46:43Z")
How about:
```julia
julia> param = :hello
:hello
julia> df = DataFrame(Dict(:a => [1, 2, 3], param=>[4, 5, 6]))
3×2 DataFrame
Row │ a hello
│ Int64 Int64
─────┼──────────────
1 │ 1 4
2 │ 2 5
3 │ 3 6
```
---
### Author:  [@waforbes](https://discourse.julialang.org/u/waforbes)
#### Post date: [March 30, 2021, 4:53pm UTC](https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248/6 "2021-03-30T16:53:02Z")
Because I corrected my rename, it does yield the desired result.
[rdeits](https://discourse.julialang.org/u/rdeits),
Is there a way to make it work in my DataFrame definition? It seems like I need to tell Julia to not take the param literally but use the param variable value.
---
### Author:  [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)
#### Post date: [March 30, 2021, 5:14pm UTC](https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248/7 "2021-03-30T17:14:09Z")
You can do this
```julia
param = "newvar"
julia> using DataFrames
julia> param = "newvar";
julia> DataFrame("StartPoint" => [1, 2], param => [3, 4])
2×2 DataFrame
Row │ StartPoint newvar
│ Int64 Int64
─────┼────────────────────
1 │ 1 3
2 │ 2 4
```
---
### Author:  [@waforbes](https://discourse.julialang.org/u/waforbes)
#### Post date: [March 30, 2021, 5:23pm UTC](https://discourse.julialang.org/t/creating-dataframe-with-column-name-that-is-a-variable/58248/8 "2021-03-30T17:23:31Z")
Thanks for the replies, everyone.