Unexpected behavior for row table

[ablaom]

I expected this:

julia> X = Tables.table(rand(10, 3))
Tables.MatrixTable{Matrix{Float64}} with 10 rows, 3 columns, and schema:
 :Column1  Float64
 :Column2  Float64
 :Column3  Float64

julia> rt = Tables.rowtable(X)
10-element Vector{NamedTuple{(:Column1, :Column2, :Column3), Tuple{Float64, Float64, Float64}}}:
 (Column1 = 0.5565428815102202, Column2 = 0.9460318649319521, Column3 = 0.3359377652605777)
 (Column1 = 0.5075982188653294, Column2 = 0.18315493443083453, Column3 = 0.9682078694091394)
 (Column1 = 0.9963268867042159, Column2 = 0.9329899214178856, Column3 = 0.5470116730645322)
 (Column1 = 0.3586863538486338, Column2 = 0.028403436910423796, Column3 = 0.37539265155858015)
 (Column1 = 0.6219233944778164, Column2 = 0.3499360310552866, Column3 = 0.14038853850080102)
 (Column1 = 0.587164895366161, Column2 = 0.9365631957076301, Column3 = 0.4638888590010579)
 (Column1 = 0.5896922517858991, Column2 = 0.29876303863960274, Column3 = 0.8361667225744209)
 (Column1 = 0.3924751962812454, Column2 = 0.7981085942387889, Column3 = 0.11151780408924594)
 (Column1 = 0.26805907763502645, Column2 = 0.6863527449570381, Column3 = 0.5322558300965325)
 (Column1 = 0.4000480227789831, Column2 = 0.5888482501962962, Column3 = 0.25538366367233634)

julia> X |> Center()
(Column1 = [0.02869116358486712, -0.020253499060023716, 0.46847516877886275, -0.16916536407671934, 0.09407167655246329, 0.059313177440807885, 0.061840533860546, -0.13537652164410774, -0.25979264029032667, -0.12780369514637002], Column2 = [0.37111666368337826, -0.39176026681773934, 0.35807472016931174, -0.5465117643381501, -0.22497917019328728, 0.36164799445905627, -0.27615216260897113, 0.223193392990215, 0.11143754370846426, 0.013933048947722293], Column3 = [-0.12067737246214477, 0.5115927316864168, 0.09039653534180975, -0.08122248616414235, -0.3162265992219215, 0.007273721278335421, 0.37955158485169843, -0.34509733363347656, 0.07564069237381005, -0.20123147405038616])

But not this:

julia> rt |> Center()
NamedTuple{(), Tuple{}}[]

[ablaom]

julia> rt |> Select(1, 3)
ERROR: BoundsError: attempt to access 0-element Vector{Union{}} at index [[1, 3]]
Stacktrace:

Mmm. What am I missing here?

[juliohm]

The issue with Center is probably because of the annoying fact that Tables.columnnames(rt) returns empty tuple for row-tables. The columnnames trait only works with column-tables. We need to first convert to Tables.columntable before proceeding with the implementation I guess?

The issue with Select may be related to the same trait. @eliascarv can you take a look at this?

[juliohm]

We should also add a lot of tests with row tables to make sure that we are not missing other issues before v1.0.

[ablaom]

Dictionary row tables also cannot be Centered or Selected:

julia> drt = Tables.dictrowtable(X);

julia> drt |> Center()
ERROR: type NamedTuple has no field names

julia> drt |> Center()
ERROR: type NamedTuple has no field names

[eliascarv]

I think the problem is in the way we are using the Tables.columnnames function.
This is the current code:

names = Tables.columnnames(table)

But this is the correct way:

cols = Tables.columns(table)
names = Tables.columnnames(cols)

[eliascarv]

I will do a PR to fix this problem.

[ablaom]

@eliascarv @juliohm Thanks for addressing this so quickly ❤️

[eliascarv]

You are welcome!