[SOLVED] I cannot use @select statement in base/tidier

I cannot use @select statement in base/tidier

I'm trying to use select statement but in both examples I'm getting an error message ERROR: LoadError: UndefVarError: @select not defined. Do you know what may causes that?

#DF
names = ["Sally", "Bob", "Alice", "Hank"]
grades = [1, 5, 8.5, 4]
df = DataFrame(; name=names, grades=grades)

#Base
@chain df begin
    @transform(:grades_new = :grades/2)
    @subset(:name .== "Sally")
    @select(:grades)
end

#Tidier
@chain df begin
    @mutate(grades_new = grades/2)
    @filter(name == "Sally")
    @select(grades)
end

Solution

There is a conflict with DataFramesMeta.@select and Tidier.@select.
Use:

using DataFrames, Chain, DataFramesMeta, Tidier

#DF
names = ["Sally", "Bob", "Alice", "Hank"]
grades = [1, 5, 8.5, 4]
df = DataFrame(; name=names, grades=grades)

#DataFramesMeta
@chain df begin
    @transform(:grades_new = :grades/2)
    @subset(:name .== "Sally")
    DataFramesMeta.@select(:grades)
end
#1×1 DataFrame
# Row │ grades  
#     │ Float64 
#─────┼─────────
#   1 │     1.0

#Tidier
@chain df begin
    @mutate(grades_new = grades/2)
    @filter(name == "Sally")
    Tidier.@select(grades)
end
#1×1 DataFrame
# Row │ grades  
#     │ Float64 
#─────┼─────────
#   1 │     1.0

In case either DataFramesMeta or Tidier is used, there is no need to qualify the module. But when they are used together, the module need to be given to know which @select will be used.