Add support for KeyedArrays as a Tables sink

README.md

@@ -140,6 +140,9 @@ while `A.keys isa Tuple` for matrices & higher. But `axiskeys(A)` always returns
 * Named tuples can be converted to and from keyed vectors,
   with `collect(keys(nt)) == Symbol.(axiskeys(V),1)`
 
+* The [Tables.jl](https://github.com/JuliaData/Tables.jl) interface is supported,
+  with `wrapdims(df, :val, :x, :y)` creating a matrix from 3 columns.
+
 * [FFTW](https://github.com/JuliaMath/FFTW.jl)`.fft` transforms the keys; 
   if these are times such as [Unitful](https://github.com/PainterQubits/Unitful.jl)`.s` 
   then the results are fequency labels. ([PR#15](https://github.com/mcabbott/AxisKeys.jl/pull/15).)

src/tables.jl

@@ -115,3 +115,104 @@ end
 
 #     end
 # end
+
+"""
+    AxisKeys.populate!(A, table, value; force=false)
+
+Populate `A` with the contents of the `value` column in a provided `table`, matching the
+[Tables.jl](https://github.com/JuliaData/Tables.jl) API. The `table` must contain columns
+corresponding to the keys in `A` and implements `Tables.rows`. If the keys in `A` do not
+uniquely identify rows in the `table` then an `ArgumentError` is throw. If `force` is true
+then the duplicate (non-unique) entries will be overwritten.
+"""
+function populate!(A, table, value::Symbol; force=false)
+    # Use a BitArray mask to detect duplicates and error instead of overwriting.
+    mask = force ? falses() : falses(size(A))
+
+    for r in Tables.rows(table)
+        vals = Tuple(Tables.getcolumn(r, c) for c in dimnames(A))
+        inds = map(findindex, vals, axiskeys(A))
+
+        # Handle duplicate error checking if applicable
+        if !force
+            # Error if mask already set.
+            mask[inds...] && throw(ArgumentError("Key $vals is not unique"))
+            # Set mask, marking that we've set this index
+            setindex!(mask, true, inds...)
+        end
+
+        # Insert our value into the data array
+        setindex!(A, Tables.getcolumn(r, value), inds...)
+    end
+
+    return A
+end
+
+"""
+    wrapdims(table, value, names...; default=undef, sort=false, force=false)
+
+Construct `KeyedArray(NamedDimsArray(A,names),keys)` from a `table` matching
+the [Tables.jl](https://github.com/JuliaData/Tables.jl) API.
+(It must support both `Tables.columns` and `Tables.rows`.)
+
+The contents of the array is taken from the column `value::Symbol` of the table.
+Each symbol in `names` specifies a column whose unique entries
+become the keys along a dimenension of the array.
+
+If there is no row in the table matching a possible set of keys,
+then this element of the array is undefined, unless you provide the `default` keyword.
+If several rows share the same set of keys, then by default an `ArgumentError` is thrown.
+Keyword `force=true` will instead cause these non-unique entries to be overwritten.
+
+Setting `AxisKeys.nameouter() = false` will reverse the order of wrappers produced.
+"""
+function wrapdims(table, value::Symbol, names::Symbol...; kw...)
+    if nameouter() == false
+        _wrap_table(KeyedArray, identity, table, value, names...; kw...)
+    else
+        _wrap_table(NamedDimsArray, identity, table, value, names...; kw...)
+    end
+end
+
+"""
+    wrapdims(df, UniqueVector, :val, :x, :y)
+
+Converts at Tables.jl table to a `KeyedArray` + `NamedDimsArray` pair,
+using column `:val` for values, and columns `:x, :y` for names & keys.
+Optional 2nd argument applies this type to all the key-vectors.
+"""
+function wrapdims(table, KT::Type, value::Symbol, names::Symbol...; kw...)
+    if nameouter() == false
+        _wrap_table(KeyedArray, KT, table, value, names...; kw...)
+    else
+        _wrap_table(NamedDimsArray, KT, table, value, names...; kw...)
+    end
+end
+
+function _wrap_table(AT::Type, KT, table, value::Symbol, names::Symbol...; default=undef, sort::Bool=false, kwargs...)
+    # get columns of the input table source
+    cols = Tables.columns(table)
+
+    # Extract key columns
+    pairs = map(names) do k
+        col = unique(Tables.getcolumn(cols, k))
+        sort && Base.sort!(col)
+        return k => KT(col)
+    end
+
+    # Extract data/value column
+    vals = Tables.getcolumn(cols, value)
+
+    # Initialize the KeyedArray
+    sz = length.(last.(pairs))
+    if default === undef
+        data = similar(vals, sz)
+    else
+        data = similar(vals, Union{eltype(vals), typeof(default)}, sz)
+        fill!(data, default)
+    end
+    A = AT(data; pairs...)
+
+    populate!(A, table, value; kwargs...)
+    return A
+end

test/_packages.jl

@@ -29,14 +29,70 @@ end
 @testset "tables" begin
     using Tables
 
-    R = wrapdims(rand(2,3), 11:12, 21:23)
-    N = wrapdims(rand(2,3), a=[11, 12], b=[21, 22, 23.0])
-
-    @test keys(first(Tables.rows(R))) == (:dim_1, :dim_2, :value)
-    @test keys(first(Tables.rows(N))) == (:a, :b, :value)
-
-    @test Tables.columns(N).a == [11, 12, 11, 12, 11, 12]
-
+    @testset "source" begin
+        R = wrapdims(rand(2,3), 11:12, 21:23)
+        N = wrapdims(rand(2,3), a=[11, 12], b=[21, 22, 23.0])
+
+        @test keys(first(Tables.rows(R))) == (:dim_1, :dim_2, :value)
+        @test keys(first(Tables.rows(N))) == (:a, :b, :value)
+
+        @test Tables.columns(N).a == [11, 12, 11, 12, 11, 12]
+    end
+    @testset "sink" begin
+        A = KeyedArray(rand(24, 11, 3); time = 0:23, loc = -5:5, id = ["a", "b", "c"])
+        table = Tables.columntable(A)
+
+        # Test fully constructing from a table
+        # Common when working with adhoc data
+        B = wrapdims(table, :value, :time, :loc, :id)
+        @test B == A
+
+        # Test wrapping of key vectors, and wrong order:
+        U = wrapdims(table, UniqueVector, :value, :id, :time, :loc)
+        @test axiskeys(U, :time) isa UniqueVector
+        @test U(time=3, id="b") == A(time=3, id="b")
+
+        # Test populating an existing array (e.g., expected data based on calculated targets/offsets)
+        C = KeyedArray(
+            zeros(Float64, size(A));
+            time = unique(table.time),
+            loc = unique(table.loc),
+            id = unique(table.id),
+        )
+        @test C != A
+        AxisKeys.populate!(C, table, :value)
+        @test C == A
+
+        # Constructing a NamedDimsArray with different default value and table type
+        # Partial populating
+        r_table = Tables.rowtable(A)
+        n = length(r_table)
+        idx = rand(Bool, n)
+        D = wrapdims(r_table[idx], :value, :time, :loc, :id; default=missing)
+        # dimnames should still match, but we'll have missing values
+        @test dimnames(D) == dimnames(A)
+        @test any(ismissing, D)
+
+        # BTW, this is why it's a method of wrapdims, not KeyedArray:
+        # @code_warntype wrapdims(table, :value, :time, :loc, :id) # ::Any
+        # @code_warntype wrapdims(r_table[idx], :value, :time, :loc, :id; default=missing)
+
+        # Construction with invalid columns error as expected, but the specific error is
+        # dependent on the table type.
+        # ERROR: ArgumentError: wrong number of names, got (:q, :time, :loc, :id) with ndims(A) == 1
+        @test_throws ArgumentError wrapdims(Tables.rowtable(A), :q, :time, :loc, :id)
+        # ERROR: ArgumentError: wrong number of names, got (:value, :p, :loc, :id) with ndims(A) == 1
+        @test_throws ArgumentError wrapdims(Tables.rowtable(A), :value, :p, :loc, :id)
+        # ERROR: type NamedTuple has no field q
+        @test_throws ErrorException wrapdims(Tables.columntable(A), :q, :time, :loc, :id)
+        # ERROR: type NamedTuple has no field p
+        @test_throws ErrorException wrapdims(Tables.columntable(A), :value, :p, :loc, :id)
+
+        # Construction with duplicates
+        # ERROR: ArgumentError: Key (Date("2019-01-01"), -5) is not unique
+        @test_throws ArgumentError wrapdims(table, :value, :time, :loc)
+        @test wrapdims(r_table, :value, :time, :loc; force=true) == C(:, :, Key("c"))
+    end
 end
 @testset "stack" begin
     using LazyStack

test/runtests.jl

@@ -9,13 +9,13 @@ using Statistics, OffsetArrays, Tables, UniqueVectors, LazyStack
         AxisKeys.nameouter() = false
     end
 
-    # include("_basic.jl")
+    include("_basic.jl")
 
     include("_functions.jl")
 
-    # include("_fast.jl")
+    include("_fast.jl")
 
-    # include("_packages.jl")
+    include("_packages.jl")
 
 end
 @testset "fast findfirst & findall" begin