ggplot不在组之间绘制连接线意味着什么？

Question

我似乎错过了ggplot2工作方式的变化。我有一个统计教科书的例子（A. Field（2012），使用R发现统计数据，第593页），我确信它已经有效，但现在不再在分组数据之间产生连接线。

以下是样本数据：

participant<-gl(20, 9, labels = c("P01", "P02", "P03", "P04", "P05", "P06", "P07", "P08", "P09", "P10", "P11", "P12", "P13", "P14", "P15", "P16", "P17", "P18", "P19", "P20" ))
drink<-gl(3, 3, 180, labels = c("Beer", "Wine", "Water"))
imagery<-gl(3, 1, 180, labels = c("Positive", "Negative", "Neutral"))
groups<-gl(9, 1, 180, labels = c("beerpos", "beerneg", "beerneut", "winepos", "wineneg", "wineneut", "waterpos", "waterneg", "waterneut"))
attitude<-c(1, 6, 5, 38, -5, 4, 10, -14, -2, 26, 27, 27, 23, -15, 14, 21, -6, 0, 1, -19, -10, 28, -13, 13, 33, -2, 9, 7, -18, 6, 26, -16, 19, 23, -17, 5, 22, -8, 4, 34, -23, 14, 21, -19, 0, 30, -6, 3, 32, -22, 21, 17, -11, 4, 40, -6, 0, 24, -9, 19, 15, -10, 2, 15, -9, 4, 29, -18, 7, 13, -17, 8, 20, -17, 9, 30, -17, 12, 16, -4, 10, 9, -12, -5, 24, -15, 18, 17, -4, 8, 14, -11, 7, 34, -14, 20, 19, -1, 12, 43, 30, 8, 20, -12, 4, 9, -10, -13, 15, -6, 13, 23, -15, 15, 29, -1, 10, 15, 15, 12, 20, -15, 6, 6, -16, 1, 40, 30, 19, 28, -4, 0, 20, -10, 2, 8, 12, 8, 11, -2, 6, 27, 5, -5, 17, 17, 15, 17, -6, 6, 9, -6, -13, 30, 21, 21, 15, -2, 16, 19, -20, 3, 34, 23, 28, 27, -7, 7, 12, -12, 2, 34, 20, 26, 24, -10, 12, 12, -9, 4)

longAttitude<-data.frame(participant, drink, imagery, groups, attitude)

这是情节代码：

library(ggplot2)
attitudeInt <- ggplot(longAttitude, aes(drink, attitude, colour = imagery))
attitudeInt + stat_summary(fun.y = mean, geom = "point") + 
              stat_summary(fun.y = mean, geom = "line", aes(group = imagery)) + 
              stat_summary(fun.data = mean_cl_boot, geom = "errorbar", width = 0.2) + 
              labs(x = "Type of Drink", y = "Mean Attitude", colour = "Type of Imagery")

部件stat_summary(fun.y = mean, geom="line", aes(group = imagery))是否应该准确地绘制这些连接线？

感谢您的帮助。

Answer 1

这不会解决ggplot2中的问题，但这是解决方法。

首先总结一下您的数据。与原始代码一样，您使用mean_cl_boot来计算置信区间，然后在此示例中也使用。

library(plyr)
dfAtt<-ddply(longAttitude,~drink+imagery,function(x) mean_cl_boot(x$attitude))

dfAtt
  drink  imagery      y      ymin     ymax
1  Beer Positive  21.05  15.65000 26.90750
2  Beer Negative   4.45  -2.60125 12.00000
3  Beer  Neutral  10.00   5.49750 14.75000
4  Wine Positive  25.35  22.40000 28.25000
5  Wine Negative -12.00 -14.40000 -9.49875
6  Wine  Neutral  11.65   8.95000 14.40125
7 Water Positive  17.40  14.40000 20.45000
8 Water Negative  -9.20 -12.25000 -6.34875
9 Water  Neutral   2.35  -0.75125  4.90000

然后绘制数据：

ggplot(dfAtt, aes(x=drink, y=y, colour=imagery,group=imagery)) + 
  geom_errorbar(aes(ymin=ymin, ymax=ymax), width=.2) +
  geom_line() +
  geom_point() +
  labs(x = "Type of Drink", y = "Mean Attitude", colour = "Type of Imagery")

Answer 2

正如Brian Diggs指出的那样，这是known bug，最近是has been fixed。因此，将ggplot2升级到0.9.3.1或更高版本应该会在stat_summary中引入正确的线条绘制行为。