add proptable

README.md

@@ -53,7 +53,7 @@ b           │ 3  2
 c           │ 2  3
 d           │ 2  3
 
-julia> prop(tbl2, 1)
+julia> prop(tbl2, 2)
 4×2 Named Array{Float64,2}
 Dim1 ╲ Dim2 │   A    B
 ────────────┼─────────

src/freqtable.jl

@@ -132,5 +132,46 @@ function freqtable(d::AbstractDataFrame, x::Symbol...; args...)
     a
 end
 
+"""
+    prop(tbl, [margin])
+
+Create table of proportions from a frequency table `tbl` with margins generated for
+dimensions specified by `margin`. Does not check if `tbl` contains non-negative frequencies.
+Calculating `sum` over the result of `prop` over dimensions that are complement of `margin`
+produces `AbstractArray` containing only approximately `1.0`, see last example below.
+
+**Arguments**
+
+* `tbl` : `AbstractArray{<:Number}` containing frequency table
+* `margin` : `Integer` or collection of `Integer`s of dimensions to generate proportions by;
+             duplicated entries are ignored, e.g. [1, 1, 2] is the same as `[1, 2]`;
+             if omitted proportions over the whole `tbl` are computed
+
+**Result**
+
+* `::AbstractArray` : array containing calculated proportions
+
+**Examples**
+
+```julia
+prop([1 2; 3 4])
+prop([1 2; 3 4], ())
+prop([1 2; 3 4], 1)
+prop([1 2; 3 4], [1])
+prop([1 2; 3 4], (1,2))
+tbl = prop(rand(5, 5, 5, 5), (1, 2))
+sumtbl = sum(tbl, (3,4))
+all(x -> x ≈ 1.0, sumtbl)
+```
+
+"""
+
 prop(tbl::AbstractArray{<:Number}) = tbl / sum(tbl)
-prop(tbl::AbstractArray{<:Number}, dims) = tbl ./ sum(tbl, dims)
+
+function prop(tbl::AbstractArray{<:Number,N}, margin) where N
+    if !all(x -> isa(x, Integer) && (1 <= x <= N), margin)
+        throw(ArgumentError("invalid margin argument; expected integers in a valid dimension range"))
+    end
+    minimum
+    tbl ./ sum(tbl, tuple(setdiff(1:N, margin)...))
+end

test/freqtable.jl

@@ -22,27 +22,32 @@ tab = @inferred freqtable(x, y)
                     0.075  0.05  0.05 0.075;
                      0.05 0.075 0.075  0.05;
                      0.05 0.075 0.075  0.05]
-@test prop(tab, (1,2)) == [0.075  0.05  0.05 0.075;
-                           0.075  0.05  0.05 0.075;
-                            0.05 0.075 0.075  0.05;
-                            0.05 0.075 0.075  0.05]
-@test prop(tab, 1) == [0.3 0.2 0.2 0.3;
+@test prop(tab, ()) == [0.075  0.05  0.05 0.075;
+                        0.075  0.05  0.05 0.075;
+                         0.05 0.075 0.075  0.05;
+                         0.05 0.075 0.075  0.05]
+@test prop(tab, 2) == [0.3 0.2 0.2 0.3;
                        0.3 0.2 0.2 0.3;
                        0.2 0.3 0.3 0.2;
                        0.2 0.3 0.3 0.2]
-@test prop(tab, 2) == [0.3 0.2 0.2 0.3;
+@test prop(tab, 1) == [0.3 0.2 0.2 0.3;
                        0.3 0.2 0.2 0.3;
                        0.2 0.3 0.3 0.2;
                        0.2 0.3 0.3 0.2]
-@test prop(tab, ()) == [1.0 1.0 1.0 1.0;
-                        1.0 1.0 1.0 1.0;
-                        1.0 1.0 1.0 1.0;
-                        1.0 1.0 1.0 1.0]
+@test prop(tab, (1, 2)) == [1.0 1.0 1.0 1.0;
+                            1.0 1.0 1.0 1.0;
+                            1.0 1.0 1.0 1.0;
+                            1.0 1.0 1.0 1.0]
+
+tbl = prop(rand(5, 5, 5, 5), (1, 2))
+sumtbl = sum(tbl, (3,4))
+@test all(x -> x ≈ 1.0, sumtbl)
 
 @test_throws MethodError prop()
-@test_throws MethodError prop([1,2,3], ("a","b"))
 @test_throws MethodError prop(("a","b"))
 @test_throws MethodError prop((1, 2))
+@test_throws ArgumentError prop([1,2,3], ("a","b"))
+@test_throws ArgumentError prop([1,2,3], 2)
 
 tab =freqtable(x, y,
                subset=1:20,
@@ -53,12 +58,12 @@ tab =freqtable(x, y,
               1.5 1.0]
 @test names(tab) == [["a", "b", "c", "d"], ["C", "D"]]
 @test prop(tab) == [4 6; 2 3; 6 4; 3 2] / 30.0
-@test prop(tab, 1) == [8  12; 4   6; 12  8; 6   4] / 30.0
-@test prop(tab, (1,)) == [8  12; 4   6; 12  8; 6   4] / 30.0
-@test prop(tab, 2) == [6 9; 6 9; 9 6; 9 6] / 15.0
-@test prop(tab, (2,)) == [6 9; 6 9; 9 6; 9 6] / 15.0
-@test prop(tab, ()) == [1.0 1.0; 1.0 1.0; 1.0 1.0; 1.0 1.0]
-@test prop(tab, (1, 2)) == [4 6; 2 3; 6 4; 3 2] / 30.0
+@test prop(tab, 2) == [8  12; 4   6; 12  8; 6   4] / 30.0
+@test prop(tab, (2,)) == [8  12; 4   6; 12  8; 6   4] / 30.0
+@test prop(tab, 1) == [6 9; 6 9; 9 6; 9 6] / 15.0
+@test prop(tab, (1,)) == [6 9; 6 9; 9 6; 9 6] / 15.0
+@test prop(tab, (1, 2)) == [1.0 1.0; 1.0 1.0; 1.0 1.0; 1.0 1.0]
+@test prop(tab, ()) == [4 6; 2 3; 6 4; 3 2] / 30.0
 
 using CategoricalArrays
 cx = CategoricalArray(x)