Welcome to the julia community!
In Gadfly, there are several ways to produce bold labels:
-
Theme(major_label_font = "Arial Bold")(the font name might be hyphenated) -
Guide.xlabel("<b>PetalWidth</b>")(this is Pango markup) - Julia unicode input (great for math symbols)
You can mix Pango and unicode, see this example
For legend inside plot, see example in the Gadfly docs