using DataFrames
df = DataFrame(a=1:3, b=4:6, c=7:9);
df1 = select(df, Not(:b) => ByRow(@_(_1 + _2)))
MethodError: no method matching +(::var"#3#5", ::var"#4#6")
Closest candidates are:
+(::Any, ::Any, !Matched::Any, !Matched::Any...) at operators.jl:529
Stacktrace:
[1] top-level scope at In[18]:1
df2 = select(df, :a => @_(_ .^2))
MethodError: no method matching ^(::var"#20#21", ::Int64)
Closest candidates are:
^(!Matched::Float16, ::Integer) at math.jl:885
^(!Matched::Regex, ::Integer) at regex.jl:712
^(!Matched::Missing, ::Integer) at missing.jl:155
...
Stacktrace:
[1] macro expansion at ./none:0 [inlined]
[2] literal_pow at ./none:0 [inlined]
[3] _broadcast_getindex_evalf at ./broadcast.jl:631 [inlined]
[4] _broadcast_getindex at ./broadcast.jl:604 [inlined]
[5] getindex at ./broadcast.jl:564 [inlined]
[6] copy at ./broadcast.jl:830 [inlined]
[7] materialize(::Base.Broadcast.Broadcasted{Base.Broadcast.DefaultArrayStyle{0},Nothing,typeof(Base.literal_pow),Tuple{Base.RefValue{typeof(^)},Base.RefValue{var"#20#21"},Base.RefValue{Val{2}}}}) at ./broadcast.jl:820
[8] top-level scope at In[23]:1