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Question

我正在嘗試使用多行和stat_summary來定義平均值。當我應用geom_errorbar（）時，它們中的一些被放置在距離平均跡象一定距離處，這意味着其中一些是「飛行」的。發生什麼事？

謝謝！

我的代碼：

#First I add another data set with SE, SD and mean. 
cdata <- ddply(data2, c("OGTT","Treatment"), summarise, 
       N = sum(!is.na(Glucose)), 
       mean = mean(Glucose, na.rm=TRUE), 
       sd = sd(Glucose, na.rm=TRUE), 
       se = sd/sqrt(N)) 


    #Then I merge it with my original data 
totalglu<-merge(data2,cdata) 

#Then I make the ggplot 
p<-ggplot(data=totalglu, aes(x = factor(OGTT), y = Glucose, group = StudyID, color=StudyID)) + 
    geom_line() + 
    facet_grid(End.start ~Treatment)+ 
    stat_summary(aes(group = Treatment), geom = "point", fun.y = mean, shape = 16, size = 2) + 
    theme(legend.position="none") + 
    labs(x = "OGTT time points (min)",y= "Glucose (mmol/l)")+ 
    geom_errorbar(aes(ymin=mean-se,ymax=mean+se), width=.1, colour="black") 
p 

My plot with flying errorbars for a some of the points

Answer 1

看來，在計算的時候吧，你不使用End.start，但它正在由stat_summary因爲小面的。

嘗試：

cdata <- ddply(data2, c("OGTT","Treatment","End.start"), summarise, 
       N = sum(!is.na(Glucose)), 
       mean = mean(Glucose, na.rm=TRUE), 
       sd = sd(Glucose, na.rm=TRUE), 
       se = sd/sqrt(N)) 


    #Then I merge it with my original data 
totalglu<-merge(data2,cdata) 

#Then I make the ggplot 
p<-ggplot(data=totalglu, aes(x = factor(OGTT), y = Glucose, group = StudyID, color=StudyID)) + 
    geom_line() + 
    facet_grid(End.start ~Treatment)+ 
    stat_summary(aes(group = Treatment), geom = "point", fun.y = mean, shape = 16, size = 2) + 
    theme(legend.position="none") + 
    labs(x = "OGTT time points (min)",y= "Glucose (mmol/l)")+ 
    geom_errorbar(aes(ymin=mean-se,ymax=mean+se), width=.1, colour="black") 
p 

雖然，沒有實際的起始數據，我不太知道什麼data2樣子，或如何ddply是影響的事情。相反，我可能會建議跳過製作cdata乾脆，只是使用：

ggplot(data=totalglu, aes(x = factor(OGTT), y = Glucose, group = StudyID, color=StudyID)) + 
    geom_line() + 
    facet_grid(End.start ~Treatment)+ 
    stat_summary(aes(group = Treatment), fun.data = mean_cl_normal) + 
    theme(legend.position="none") + 
    labs(x = "OGTT time points (min)",y= "Glucose (mmol/l)")