extracting from a TimeArray another one by columns - time-series

Question

I have a julia TimeArray, let's say ta, and I want to build sub_array a TimeArray sub_ta by extracting some of the columns. Some month ago, I used a code similar to minimal example below, but which doesn't work anymore
import TimeSeries
import Dates
dates_index = [ Dates.Date(1970,1,day) for day in [1,2,3,4,5] ]
values = [ [1.0 2.0 3.0 4.0 5.0] ; [10.0 20.0 30.0 40.0 50.0] ; [ 100.0 200.0 300.0 400.0 500.0] ]
ta = TimeSeries.TimeArray( dates_index, transpose(values), [ :col1, :col2, :col3 ] )
sub_ta = ta[ [ :col1 , :col2 ] ]
ERROR: MethodError: no method matching getindex(::TimeSeries.TimeArray{Float64,2,Dates.Date,LinearAlgebra.Transpose{Float64,Array{Float64,2}}}, ::Array{Symbol,1})
Closest candidates are:
getindex(::TimeSeries.TimeArray, ::Integer) at /home/guilhem/.julia/packages/TimeSeries/bbwst/src/timearray.jl:259
getindex(::TimeSeries.TimeArray, ::UnitRange{#s30} where #s30<:Integer) at /home/guilhem/.julia/packages/TimeSeries/bbwst/src/timearray.jl:268
getindex(::TimeSeries.TimeArray, ::AbstractArray{#s30,1} where #s30<:Integer) at /home/guilhem/.julia/packages/TimeSeries/bbwst/src/timearray.jl:276
What seems strange to me is that there is, in the source of the TimeSeries library (in the file timearray.jl) a function getindex which should work if we want to work on many columns.
# array of columns by name
function getindex(ta::TimeArray, ss::Symbol...)
ns = [findcol(ta, s) for s in ss]
TimeArray(timestamp(ta), values(ta)[:, ns], collect(ss), meta(ta))
end
But I think I didn't get the proper way to use it, probably due to the splat operator what I don't really master
problem is both on julia-1.1.0 and julia-1.3.1, with TimeSeries v0.14.0

Answer 1

Finally I think I found the solution, I was quite close :
sub_ta = ta[ [:col1 , col2]...]
The best introduction I found on the ..., the splat operator is on this page (search "..." or "splat") :
enter link description here

Answer 2

What version of TimeSeries are you using?
(tmp) pkg> status
Status `/tmp/Project.toml`
[9e3dc215] TimeSeries v0.16.1
In version 0.16.1, both syntaxes that you mention seem to work:
julia> ta
5×3 TimeSeries.TimeArray{Float64,2,Dates.Date,LinearAlgebra.Transpose{Float64,Array{Float64,2}}} 1970-01-01 to 1970-01-05
│ │ col1 │ col2 │ col3 │
├────────────┼───────┼───────┼───────┤
│ 1970-01-01 │ 1.0 │ 10.0 │ 100.0 │
│ 1970-01-02 │ 2.0 │ 20.0 │ 200.0 │
│ 1970-01-03 │ 3.0 │ 30.0 │ 300.0 │
│ 1970-01-04 │ 4.0 │ 40.0 │ 400.0 │
│ 1970-01-05 │ 5.0 │ 50.0 │ 500.0 │
julia> ta[[:col1, :col2]]
5×2 TimeSeries.TimeArray{Float64,2,Dates.Date,Array{Float64,2}} 1970-01-01 to 1970-01-05
│ │ col1 │ col2 │
├────────────┼───────┼───────┤
│ 1970-01-01 │ 1.0 │ 10.0 │
│ 1970-01-02 │ 2.0 │ 20.0 │
│ 1970-01-03 │ 3.0 │ 30.0 │
│ 1970-01-04 │ 4.0 │ 40.0 │
│ 1970-01-05 │ 5.0 │ 50.0 │
julia> ta[[:col1, :col2]...]
5×2 TimeSeries.TimeArray{Float64,2,Dates.Date,Array{Float64,2}} 1970-01-01 to 1970-01-05
│ │ col1 │ col2 │
├────────────┼───────┼───────┤
│ 1970-01-01 │ 1.0 │ 10.0 │
│ 1970-01-02 │ 2.0 │ 20.0 │
│ 1970-01-03 │ 3.0 │ 30.0 │
│ 1970-01-04 │ 4.0 │ 40.0 │
│ 1970-01-05 │ 5.0 │ 50.0 │
Note that this last version is a rather convoluted way of writing ta[:col1, :col2]:
julia> ta[:col1, :col2]
5×2 TimeSeries.TimeArray{Float64,2,Dates.Date,Array{Float64,2}} 1970-01-01 to 1970-01-05
│ │ col1 │ col2 │
├────────────┼───────┼───────┤
│ 1970-01-01 │ 1.0 │ 10.0 │
│ 1970-01-02 │ 2.0 │ 20.0 │
│ 1970-01-03 │ 3.0 │ 30.0 │
│ 1970-01-04 │ 4.0 │ 40.0 │
│ 1970-01-05 │ 5.0 │ 50.0 │