Can the frame border on a BarChart Legend be removed?

Question

I am creating an application for various kinds of plot/chart drawing in Mathematica. Ultimately it will have a GUI, but the first step is to get the code right, and simple e

Answer 1

I can't find any options to turn the frame off. The documentation for LegendAppearance is fairly minimal and the styling of legends in general does not get much discussion (see [2] and links within).

The easiest solution I can think of is to manually modify the graphics. Charts with legends produce Labeled graphics objects. For a single legend, the Labeled object that is produced looks like Labeled[Graphics[...], Framed[...], pos], so all you need to do is remove the Framed part. This could be done just be removing all Framed heads using a ReplaceAll (e.g. BarChart[...] /. Framed -> Identity), but maybe something more targeted would be safer.

mydata = {4.5644, 5.546, 6.8674, 2.7688, 1.742, 5.3952, 4.3392, 
   4.5016, 3.7748, 1.838, 2.24, 0.693, 2.818, 4.9, 3.939, 3.459, 
   3.755, 4.475, 3.857, 3.215, 2.206, 2.206, 2.117, 3.403, 3.277, 
   3.761, 4.276, 2.559, 3.486, 4.778, 2.281, 2.865, 3.629, 4.916, 
   4.572, 5.244, 5.395, 2.865, -0.524, 5.01, 4.401, 4.513, 4.54};

bc = BarChart[{Legended[Style[mydata[[;; -4]], Red], "Data"], 
   Legended[Style[mydata[[-3 ;;]], Blue], "Forecasts"]}, 
  PlotRange -> {-2, 8}, BarSpacing -> 0.4, LegendAppearance -> "Row"]

bc /. Labeled[g_, Framed[leg_], pos_] :> Labeled[g, leg, pos]

The above could also be produced using Replace[bc, Framed[leg_] :> leg, {1}] or MapAt[Apply[Identity, #] &, bc, 2] or similar constructions. It wouldn't take much to modify the code if you have more labels or different types of graphics objects.