如何在Julia的StatsPlots groupedbar中自定义X轴图例顺序

使用Julia的StatsPlots绘制分组柱状图时，图例会按名称自动排序，无法保持自定义顺序，代码如下：

legends = repeat(["myopic baseline", "vfa", "lvfa", "nnvfa", "nnvfa with attention"], outer=2)
training_time_per_step = [0., 9.817792895793914, 6.380393509864807, 15.770121607780457, 31.79437662124634]
eval_time_per_step = [2.756498346328735, 6.823106627861659, 6.184429474310442, 13.286595929535952, 20.297245191227304]
ctg = repeat(["training time per step", "eval time per step"], inner = 5)
bar1 = groupedbar(legends, vcat(training_time_per_step, eval_time_per_step), group=ctg, xlabel="Methods", ylabel="Time", 
title="Time Evaluation", legend=:topleft, reuse=false)
display(bar1)

希望图例保持["training time per step", "eval time per step"]的定义顺序，而非自动排序后的结果。

StatsPlots默认会对分组变量按字典序排序，要保留自定义顺序，需将分组变量ctg转换为有序分类类型，并指定目标顺序。具体实现：

1. 导入CategoricalArrays包（未安装先执行using Pkg; Pkg.add("CategoricalArrays")）
2. 用CategoricalArray创建有序分类，通过levels参数指定图例顺序，同时设置ordered=true

修改后的完整代码：

using StatsPlots
using CategoricalArrays

# 定义方法名称和时间数据
method_names = ["myopic baseline", "vfa", "lvfa", "nnvfa", "nnvfa with attention"]
training_time_per_step = [0., 9.817792895793914, 6.380393509864807, 15.770121607780457, 31.79437662124634]
eval_time_per_step = [2.756498346328735, 6.823106627861659, 6.184429474310442, 13.286595929535952, 20.297245191227304]

# 将分组变量转为有序分类，指定自定义顺序
ctg_order = ["training time per step", "eval time per step"]
ctg = repeat(CategoricalArray(ctg_order, ordered=true), inner=5)

# 构造x轴标签
legends = repeat(method_names, outer=2)

# 绘制分组柱状图
bar1 = groupedbar(legends, vcat(training_time_per_step, eval_time_per_step), group=ctg, 
                  xlabel="Methods", ylabel="Time", title="Time Evaluation", 
                  legend=:topleft, reuse=false)
display(bar1)

处理后，图例将严格按照定义的["training time per step", "eval time per step"]顺序显示，不会再自动排序。

内容的提问来源于stack exchange，提问作者PokeLu