add feature to change x-axis order for boxplots (#483)

* add feature to change x-axis order for boxplots

* change name of new parameter to order_labels_by

* fix typo

* correctly formatted new changes

* Update src/boxplot.jl

---------

Co-authored-by: Seth Axen <seth@sethaxen.com>
Co-authored-by: Seth Axen <seth.axen@gmail.com>

src/boxplot.jl

@@ -13,6 +13,7 @@ notch_width(q2, q4, N) = 1.58 * (q4 - q2) / sqrt(N)
     whisker_range = 1.5,
     outliers = true,
     whisker_width = :half,
+    sort_labels_by = identity,
     xshift = 0.0,
 )
     # if only y is provided, then x will be UnitRange 1:size(y,2)
@@ -32,7 +33,7 @@ notch_width(q2, q4, N) = 1.58 * (q4 - q2) / sqrt(N)
     isnothing(bw) && (bw = 0.8)
     @assert whisker_width === :match || whisker_width == :half || whisker_width >= 0 "whisker_width must be :match, :half, or a positive number"
     ww = whisker_width === :match ? bw : whisker_width == :half ? bw / 2 : whisker_width
-    for (i, glabel) in enumerate(glabels)
+    for (i, glabel) in enumerate(sort(glabels; by = sort_labels_by))
         # filter y
         values = y[filter(i -> _cycle(x, i) == glabel, 1:length(y))]