How to get a reference to the row number from a julia dataframe?

Question

In Julia, dataframes are output with a sequential row number. I would like to access the row numbers as if it were a ROWID in the dataframe. I need this to calculate a regression.

Right now I do this with trick to add an extra column (x1) to mimic the rowid:

data = hcat(data, collect(1:size(data,1)));
glm(Column ~ x1, data, Normal(), IdentityLink())

I would like to achieve this directly, without adding an extra x1 column to the table. The x1 column I use now is a workaround. So what I'd like to achieve is to get the first line that adds an extra column. If the x1 column is not added, the glm() function crashes. So I need to find a direct replacement for the x1 in the glm() function (if that is possible).

Is there a simple way to get to the rowid of the tableframe?

Answer 1

Starting from DataFrames v0.22.0 rownumber(dfr::DataFrameRow) returns the row number.

julia> data = DataFrame(a=4:6, b=7:9)
3×2 DataFrame
 Row │ a      b     
     │ Int64  Int64 
─────┼──────────────
   1 │     4      7
   2 │     5      8
   3 │     6      9

julia> rownumber.(eachrow(data))
3-element Array{Int64,1}:
 1
 2
 3