怎么调整Ggplot2柱状图中的顺序条？

Question

我正在尝试做一个柱状图，其中最大的柱状图最接近 y 轴，最短的柱状图最远。表格如下：

    Name   Position
1   James  Goalkeeper
2   Frank  Goalkeeper
3   Jean   Defense
4   Steve  Defense
5   John   Defense
6   Tim    Striker

因此，我试图建立一个条形图，将球员人数根据位置显示：

p <- ggplot(theTable, aes(x = Position)) + geom_bar(binwidth = 1)

但图表显示的是守门员横杆，然后是防守队员，最后是前锋队员。 、我希望这个图表被排列整齐，使得防守柱最接近 y 轴，守门员柱，最后是射手柱。谢谢。

Answer 1

The key with ordering is to set the levels of the factor in the order you want. An ordered factor is not required; the extra information in an ordered factor isn't necessary and if these data are being used in any statistical model, the wrong parametrisation might result — polynomial contrasts aren't right for nominal data such as this.

## set the levels in order we want
theTable <- within(theTable, 
                   Position <- factor(Position, 
                                      levels=names(sort(table(Position), 
                                                        decreasing=TRUE))))
## plot
ggplot(theTable,aes(x=Position))+geom_bar(binwidth=1)

In the most general sense, we simply need to set the factor levels to be in the desired order. If left unspecified, the levels of a factor will be sorted alphabetically. However, there are multiple ways to change the order to a specific sequence depending on the situation. For instance, we could do:

levels(theTable$Position) <- c(...)

and simply list the levels in the desired order on the right hand side. You can also specify the level order within the call to factor as above:

theTable$Position <- factor(theTable$Position, levels = c(...))