Eachcol get name property

How can I get the name property when using eachcol?

You are talking about DataFrames.eachcol right? It seems that in a loop you just get an array.

julia> dfq = DataFrame(a = [3, 4], b = ["ali", "baba"])
2Γ—2 DataFrame
β”‚ Row β”‚ a     β”‚ b      β”‚
β”‚     β”‚ Int64 β”‚ String β”‚
β”‚ 1   β”‚ 3     β”‚ ali    β”‚
β”‚ 2   β”‚ 4     β”‚ baba   β”‚

julia> for col in eachcol(dfq)
       println(col, ' ', typeof(col))
[3, 4] Array{Int64,1}
["ali", "baba"] Array{String,1}

So what about:

julia> for name in names(dfq)
       col = dfq[name]
       println(name, ": ", col)
a: [3, 4]
b: ["ali", "baba"]

You can also iterate through pairs(eachcol(df))

julia> for (name, col) in pairs(eachcol(df))
       @show name

I did something similar. I want to know how to access the name property.

Ua! Hard to get it. Don’t know how it works, but yes, this works!

Here’s how it works:

julia> using DataFrames

julia> df = DataFrame(rand(10, 10));

julia> @which pairs(eachcol(df))
pairs(itr::DataFrames.DataFrameColumns) in DataFrames at /home/nils/.julia/packages/DataFrames/cdZCk/src/abstractdataframe/iteration.jl:200

so the pairs method being called is implemented here:

Base.pairs(itr::DataFrameColumns) = Base.Iterators.Pairs(itr, keys(itr))

and the DataFrameColumns object comes from here:

eachcol(df::AbstractDataFrame) = DataFrameColumns(df)