ggplot2中直方图条形的反向填充顺序

我注意到，使用绘图创建的直方图中填充条形的默认情况是按字母顺序逆序排列，而图例则按字母顺序排列。我有什么办法让两者按字母顺序排序吗？问题在下面的示例图中很明显。额外问题：如何将从左到右的条形顺序从字母顺序更改为递减计数总数？谢谢

df <- data.frame(
  Site=c("A05","R17","R01","A05","R17","R01"),
  Group=c("Fungia","Fungia","Acro","Acro","Porites","Porites"),
  Count=c(6,8,6,7,2,9),
  Total=c(13,10,15,13,10,15)
)

  Site   Group Count Total
1  A05  Fungia     6    13
2  R17  Fungia     8    10
3  R01    Acro     6    15
4  A05    Acro     7    13
5  R17 Porites     2    10
6  R01 Porites     9    15

qplot(df$Site,data=df,weight=df$Count,geom="histogram", fill=df$Group, ylim = c(0,16)) + 
  xlab("Sites") + 
  ylab("Counts") + 
  scale_fill_hue(h=c(0,360), l=70, c=70,name = "Emergent Groups")

我正在尝试从高到低对计数和填充颜色进行排序，以便它们与图例的字母顺序相匹配。我已经尝试根据最初帖子中的提示调整它几个小时，但没有成功。对此的任何帮助将不胜感激！

如果您只想颜色顺序匹配，则可以反转图例：颜色顺序将匹配，但图例将按相反的字母顺序排列：

qplot(df$Site,data=df,weight=df$Count,geom="histogram", fill=df$Group, ylim = c(0,16)) + 
  xlab("Sites") + 
  ylab("Counts") + 
  scale_fill_hue(h=c(0,360), l=70, c=70,name = "Emergent Groups") +
  guides(fill = guide_legend(reverse = TRUE))

要恢复字母顺序，请在上述代码之前对 Group 因子进行重新排序：

# reorder the groups
df$Group <- factor(df$Group , 
                   levels=levels(df$Group)[order(levels(df$Group), decreasing = TRUE)])

qplot(df$Site,data=df,weight=df$Count,geom="histogram", fill=df$Group, ylim = c(0,16)) + 
  xlab("Sites") + 
  ylab("Counts") + 
  scale_fill_hue(h=c(0,360), l=70, c=70,name = "Emergent Groups") +
  guides(fill = guide_legend(reverse = TRUE))

为了获得奖励（通过减少总计数对条形进行排序），请重新排序 Site 变量的因子顺序：

# reorder the sites
df$Site <- factor(df$Site, 
                  levels = levels(df$Site)[order(aggregate(Count ~ Site, data = df, sum)$Count, 
                                                 decreasing = TRUE)])
# reorder the groups
df$Group <- factor(df$Group , 
                   levels=levels(df$Group)[order(levels(df$Group), decreasing = TRUE)])

qplot(df$Site,data=df,weight=df$Count,geom="histogram", fill=df$Group, ylim = c(0,16)) + 
  xlab("Sites") + 
  ylab("Counts") + 
  scale_fill_hue(h=c(0,360), l=70, c=70,name = "Emergent Groups") +
  guides(fill = guide_legend(reverse = TRUE))