error in dataframe when using geom_errorbar?

Question

My dataframe (df) looks like this:

   df
 me  SD class  
 3.11 4.08  A
 2.09 3.50  B
 1.75 2.72  C
 0.34 0.85  D

Where me is the mean and SD is the standard deviation. I want to create a barplot of these mean values for each class and add the standard deviation on top of those bars:

To plot the bars:

ggplot(data=df) +
  geom_bar(aes(x=class,y= me), 
           stat="identity",position="dodge")+ 
  ylab("mean")+ 
  xlab("class")+ 
  theme(
    text = element_text(size=20, colour="black"),  
    axis.text.x = element_text(angle=90, vjust=1, colour="black"), 
    axis.text.y = element_text(colour="black")) + 
  scale_y_continuous(breaks = round(seq(-2, 5, by = 0.5),1))

This works fine.

Now add the error-bar:

ggplot(data=df3) +
  geom_bar(aes(x=class,y= me), 
           stat="identity",position="dodge")+ 
  ylab("mean")+   
  xlab("class")+ 
  theme(
    text = element_text(size=20, colour="black"),  
    axis.text.x = element_text(angle=90, vjust=1, colour="black"), 
    axis.text.y = element_text(colour="black"))+ 
  scale_y_continuous(breaks = round(seq(-2, 5, by = 0.5),1))+ 
  geom_errorbar(aes(ymax = me + SD, ymin= me - SD), 
                position=position_dodge(0.9))

I got this error:

   Error in data.frame(list(ymin = c(-1.96681604736652, -1.40293149619775,  : 
    arguments imply differing number of rows: 28, 102

DatamineR · Accepted Answer · 2015-11-13 14:42:40Z

2

Define x and y wthin the ggplot:

ggplot(data=df, aes(x = class, y = me)) + 
geom_bar(stat="identity",position="dodge")+ ylab("mean")+   
xlab("class") + theme(text = element_text(size=20, colour="black"),  
axis.text.x = element_text(angle=90, vjust=1, colour="black"), 
axis.text.y = element_text(colour="black"))+ scale_y_continuous(breaks 
= round(seq(-2, 5, by = 0.5),1)) + geom_errorbar(aes(ymax = me + SD, 
ymin= me - SD), position=position_dodge(0.9))

Alternatively:

ggplot(data=df, aes(x = class, y = me)) + 
    geom_bar(stat="identity",position="dodge")+ ylab("mean")+   
    xlab("class") + theme(text = element_text(size=20, colour="black"),  
                          axis.text.x = element_text(angle=90, vjust=1, colour="black"), 
                          axis.text.y = element_text(colour="black"))+ scale_y_continuous(breaks 
                                                                                          = round(seq(-2, 5, by = 0.5),1)) + geom_errorbar(aes(ymax = SD, 
                                                                                                                                               ymin= me - (SD-me)), position=position_dodge(0.9))

edited Nov 13, 2015 at 14:42

answered Nov 13, 2015 at 14:05

DatamineR

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3 Comments

DatamineR Over a year ago

They are plotted as you defined them in the geom_errorbar function. Do you want to include the numbers in the plot?

DatamineR Over a year ago

What about the second version?

DatamineR Over a year ago

It creates a symmetric range

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