geom_errorbar

geom_errorbar(mapping=NULL, data=NULL, stat="identity", position="identity", ...)

Error bars

This page describes geom_errorbar, see layer and qplot for how to create a complete plot from individual components.

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Aesthetics

The following aesthetics can be used with geom_errorbar. Aesthetics are mapped to variables in the data with the aes function: geom_errorbar(aes(x = var)). Note that you do not need quotes around the variable name.

Scales control how the variable is mapped to the aesthetic and are listed after each aesthetic.

Aesthetic	Default	Related scales
x	required	continuous, date, datetime, discrete
ymin	required
ymax	required
colour	black	brewer, gradient, gradient2, gradientn, grey, hue, identity, manual
size	0.5	identity, manual, size
linetype	1	identity, linetype, manual
width	0.5
alpha	1

Layers are divided into groups by the group aesthetic. By default this is set to the interaction of all categorical variables present in the plot.

Parameters

Parameters control the appearance of the geom. In addition to the parameters listed below (if any), any aesthetic can be used as a parameter, in which case it will override any aesthetic mapping.

Returns

This function returns a layer object.

Examples

> # Create a simple example dataset 
> df <- data.frame( 
+   trt = factor(c(1, 1, 2, 2)), 
+   resp = c(1, 5, 3, 4), 
+   group = factor(c(1, 2, 1, 2)), 
+   se = c(0.1, 0.3, 0.3, 0.2) 
+ ) 
> df2 <- df[c(1,3),] 
>  
> # Define the top and bottom of the errorbars 
> limits <- aes(ymax = resp + se, ymin=resp - se) 
>  
> p <- ggplot(df, aes(fill=group, y=resp, x=trt)) 
> p + geom_bar(position="dodge", stat="identity") 
  
>  
> # Because the bars and errorbars have different widths 
> # we need to specify how wide the objects we are dodging are 
> dodge <- position_dodge(width=0.9) 
> p + geom_bar(position=dodge) + geom_errorbar(limits, position=dodge, width=0.25) 
  
>  
> p <- ggplot(df2, aes(fill=group, y=resp, x=trt)) 
> p + geom_bar(position=dodge) 
  
> p + geom_bar(position=dodge) + geom_errorbar(limits, position=dodge, width=0.25) 
  
>  
> p <- ggplot(df, aes(colour=group, y=resp, x=trt)) 
> p + geom_point() + geom_errorbar(limits, width=0.2) 
  
> p + geom_pointrange(limits) 
  
> p + geom_crossbar(limits, width=0.2) 
  
>  
> # If we want to draw lines, we need to manually set the 
> # groups which define the lines - here the groups in the 
> # original dataframe 
> p + geom_line(aes(group=group)) + geom_errorbar(limits, width=0.2)