Creating new macros

[JockLawrie]

Hi there,

I am creating some new macros for use with the @linq macro. I can create the macros, but I can't get @linq to recognize them. Simple example below. Any ideas?

using DataFrames
using DataFramesMeta

# simple renaming of where macro
macro selectrows(d, args...)
    esc(DataFramesMeta.where_helper(d, args...))
end

function linq(::DataFramesMeta.SymbolParameter{:selectrows}, d, args...)
    DataFramesMeta.where_helper(d, args...)
end

df = DataFrame(x = 1:3, y = [2, 1, 2]);
@linq df |> @selectrows(:x .> 1)    # OK
@linq df |> selectrows(:x .> 1)     # Error

The error is:

ERROR: MethodError: no method matching isless(::Int64, ::Symbol)
Closest candidates are:
  isless(::Symbol, ::Symbol) at strings/basic.jl:136
  isless(::DataArrays.NAtype, ::Any) at /home/jock/.julia/v0.6/DataArrays/src/operators.jl:383
  isless(::Real, ::AbstractFloat) at operators.jl:97
  ...
Stacktrace:
 [1] (::##97#98)(::Symbol) at ./<missing>:0
 [2] broadcast(::Function, ::Symbol) at ./broadcast.jl:434

[tshort]

I'm not at a computer to try it, but I think you need to define that linq method as DataFramesMeta.linq.

[JockLawrie]

Ah, yes that did it, thanks.

FYI - I'm mostly just renaming some macros so that I can remember what I did 6 months later. I have:

• selectcols (renamed from select)
• selectrows (renamed from where)
• appendcols! (renamed from transform and check that column names do not already exist)
• mutatecols! (renamed from transform and check that column names already exist)
• orderby and by unchanged

Thanks again.