stokes I fix

Author: aplavin

src/polarizedtypes.jl

@@ -19,11 +19,10 @@ function uvtable_values_to(::Type{CoherencyMatrix}, uvtbl)
 end
 
 function uvtable_values_to(::Type{IPol}, uvtbl)
-	grs = @p uvtbl group_vg((;_.datetime, _.freq_spec, _.spec))
+	grs = @p uvtbl filter(is_parallel_hands(_.stokes)) group_vg((;_.datetime, _.freq_spec, _.spec))
 	return map(grs) do gr
-		par_hands = @p gr filter(x -> is_parallel_hands(x.stokes))
-		length(par_hands) ∈ (1, 2) || error("expected 1 or 2 parallel-hand Stokes per group, got $(length(par_hands))")
-		val = mean(x -> x.value, par_hands)
+		length(gr) ∈ (1, 2) || error("expected 1 or 2 parallel-hand Stokes per group, got $(length(gr))")
+		val = mean(x -> x.value, gr)
 		@p let
 			first(gr)
 			@set __.value = val

test/runtests.jl

@@ -297,12 +297,12 @@ end
     @test length(ipol_single_ll) == 1
     @test ipol_single_ll[1].value == 7.0
 
-    # IPol: error when no parallel hands
+    # IPol: when no parallel hands
     uvtbl_no_par = [
         (datetime=1, freq_spec=100.0, spec=1, stokes=:LR, value=12.0),
         (datetime=1, freq_spec=100.0, spec=1, stokes=:RL, value=13.0),
     ]
-    @test_throws "expected 1 or 2 parallel-hand" VLBI.uvtable_values_to(IPol, uvtbl_no_par)
+    @test isempty(VLBI.uvtable_values_to(IPol, uvtbl_no_par))
 end
 
 @testitem "_" begin