code: def _ggplot(df, out_file):
      
      import ggplot as gg
      df["variant.type"] = [vtype_labels[x] for x in df["variant.type"]]
      df["category"] = [cat_labels[x] for x in df["category"]]
      df["caller"] = [caller_labels.get(x, None) for x in df["caller"]]
      p = (gg.ggplot(df, gg.aes(x="caller", y="value.floor")) + gg.geom_bar()
           + gg.facet_wrap("variant.type", "category")
           + gg.theme_seaborn())
      gg.ggsave(p, out_file)
docs: Plot faceted items with ggplot wrapper on top of matplotlib.
      XXX Not yet functional