ToolJuliaBeginner DataFrames.jl from the ground up: a week of temperature logs counts = combine(g, sensors .=> nvalid .=> sensors)hourly = combine(g, sensors .=> covered_mean .=> sensors)cycle = combine(groupby(df, :hourofday), sensors .=> skipmean .=> sensors)daily = combine(groupby(df, :day), :t2 => skipmean => :mean, :t2 => nvalid => :minutes)