Add support for strings in compose function (#44)

* Add support for strings in 'compose' function

* Apply suggestions

* Update README

README.md

@@ -187,9 +187,9 @@ julia> table = (a=[1,2,3], b=[4,5,6], c=[7,8,9])
 (a = [1, 2, 3], b = [4, 5, 6], c = [7, 8, 9])
 
 julia> ctable = compose(table, (:a,:b))
-(c = [7, 8, 9], coda = Composition{2, (:a, :b)}["1.000 : 4.000", "2.000 : 5.000", "3.000 : 6.000"])
+(c = [7, 8, 9], CODA = Composition{2, (:a, :b)}[1.000 : 4.000, 2.000 : 5.000, 3.000 : 6.000])
 
-julia> ctable.coda[1]
+julia> ctable.CODA[1]
                 2-part composition
      ┌                                        ┐ 
    a ┤■■■■■■■■■ 1.0                             

src/codaarrays.jl

@@ -41,26 +41,27 @@ Parts in compositional `array`.
 parts(::CoDaArray{D,PARTS}) where {D,PARTS} = PARTS
 
 """
-    compose(table, colnames; keepcols=true, as=:coda)
+    compose(table, colnames; keepcols=true, as=:CODA)
 
 Convert columns `colnames` of `table` into parts of a
 composition and save the result in a [`CoDaArray`](@ref).
 If `keepcols` is set to `true`, then save the result `as`
 a column in a new table with all other columns preserved.
 """
-function compose(table, colnames=Tables.columnnames(Tables.columns(table)); keepcols=true, as=:coda)
+function compose(table, colnames=nothing; keepcols=true, as=:CODA)
   cols = Tables.columns(table)
   names = Tables.columnnames(cols)
-  scols = (nm => Tables.getcolumn(cols, nm) for nm in colnames)
+  snames = isnothing(colnames) ? names : Symbol.(colnames)
+  scols = (nm => Tables.getcolumn(cols, nm) for nm in snames)
   # construct compositional array from selected columns
   coda = (; scols...) |> CoDaArray
 
   # different types of return
   if keepcols
-    other = setdiff(names, colnames)
+    other = setdiff(names, snames)
     ocols = (nm => Tables.getcolumn(cols, nm) for nm in other)
     # preserve input table type
-    (; ocols..., as => coda) |> Tables.materializer(table)
+    (; ocols..., Symbol(as) => coda) |> Tables.materializer(table)
   else
     coda
   end

test/codaarrays.jl

@@ -27,13 +27,17 @@
   @test_throws KeyError array.INVALID
 
   table = compose(jura, (:Cd, :Cu, :Pb, :Co, :Cr, :Ni, :Zn))
-  @test Tables.columnnames(table) == [:X, :Y, :Rock, :Land, :coda]
-  @test Tables.getcolumn(table, :coda) == array
+  @test Tables.columnnames(table) == [:X, :Y, :Rock, :Land, :CODA]
+  @test Tables.getcolumn(table, :CODA) == array
 
   table = compose(jura, (:Cd, :Cu, :Pb, :Co, :Cr, :Ni, :Zn), as=:comps)
   @test Tables.columnnames(table) == [:X, :Y, :Rock, :Land, :comps]
   @test Tables.getcolumn(table, :comps) == array
 
+  table = compose(jura, ("Cd", "Cu", "Pb", "Co", "Cr", "Ni", "Zn"), as="comps")
+  @test Tables.columnnames(table) == [:X, :Y, :Rock, :Land, :comps]
+  @test Tables.getcolumn(table, :comps) == array
+
   # performance test
   rng = MersenneTwister(2)
   N = 100_000