我正在关注https://github.com/JuliaComputing/JuliaDB.jl/blob/master/docs/src/tutorial.md
上发布的教程
a) 执行时:
summarize(mean ∘ skipmissing, flights, :Dest, select = (:Cancelled, :Diverted))
得到:
Error: UndefVarError: mean not defined
b)还尝试过:
summarize(mean, dropna(flights), select = :dep_delay)
得到:
Error: UndefVarError: dropna not defined
请帮我解决问题!