dataframes-tuplerow.jl

function f(df)
    x = 0.0
    cols = DataFrames.columns(df)
    for i in 1:nrow(df)
        t = ntuple(j -> cols[j][i], ncol(df))
        x += t[1]
    end
    x
end

function g(df)
    x = 0.0
    for i in 1:nrow(df)
        r = DataFrameRow(df, i)
        x += r[1]
    end
    x
end

using DataFrames, BenchmarkTools
df = DataFrame(x=rand(1000), y=rand(1000))
df2 = DataFrame(rand(1000, 100))

julia> @btime f(df);
  279.796 μs (6979 allocations: 140.30 KiB)

julia> @btime f(df2);
  6.715 ms (256901 allocations: 5.58 MiB)

julia> @btime g(df);
  40.277 μs (2490 allocations: 38.91 KiB)

julia> @btime g(df2);
  40.183 μs (2490 allocations: 38.91 KiB)