Convert String to Number while maintaining 'missing's

New to Julia
, ,
7

Oh, thank you for clearing that up.

When I try various interations of passmissing(parse)(Float64,df) in the REPL, I get the following error.

 MethodError: no method matching parse(::Type{Float64}, ::DataFrame)
Closest candidates are:
  parse(::Type{T}, ::AbstractString; kwargs...) where T<:Real at parse.jl:379
Stacktrace:
 [1] macro expansion
   @ ~\.julia\packages\Missings\hn4Ye\src\Missings.jl:0 [inlined]
 [2] (::Missings.PassMissing{typeof(parse)})(::Type{Float64}, ::DataFrame)
   @ Missings ~\.julia\packages\Missings\hn4Ye\src\Missings.jl:195
 [3] top-level scope
   @ REPL[37]:1

I have tried

parse.(Float64,passmissing(df[!,:Length]))
passmissing(parse.(Float64,df[!,:Length]))
parse(Float64,passmissing(df.Length))
passmissing(parse(Float64,df.Length))

All of whom gave a long error stack

Closest candidates are:
  parse(::Type{T}, ::AbstractString; kwargs...) where T<:Real at parse.jl:379
Stacktrace:
  [1] _broadcast_getindex_evalf
    @ .\broadcast.jl:648 [inlined]
  [2] _broadcast_getindex
    @ .\broadcast.jl:631 [inlined]
  [3] getindex
    @ .\broadcast.jl:575 [inlined]
  [4] macro expansion
    @ .\broadcast.jl:984 [inlined]
  [5] macro expansion
    @ .\simdloop.jl:77 [inlined]
  [6] copyto!
    @ .\broadcast.jl:983 [inlined]
  [7] copyto!
    @ .\broadcast.jl:936 [inlined]
  [8] copy
    @ .\broadcast.jl:908 [inlined]
  [9] materialize(bc::Base.Broadcast.Broadcasted{Base.Broadcast.DefaultArrayStyle{1}, Nothing, typeof(parse), Tuple{Base.RefValue{Type{Float64}}, Vector{Union{Missing, String}}}})
    @ Base.Broadcast .\broadcast.jl:883
 [10] top-level scope
    @ REPL[40]:1