Error bars.

Usage

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

Arguments

mapping
The aesthetic mapping, usually constructed with aes or aes_string. Only needs to be set at the layer level if you are overriding the plot defaults.
data
A layer specific dataset - only needed if you want to override the plot defaults.
stat
The statistical transformation to use on the data for this layer.
position
The position adjustment to use for overlappling points on this layer
...
other arguments passed on to layer. This can include aesthetics whose values you want to set, not map. See layer for more details.

Description

Error bars.

Aesthetics

geom_errorbar understands the following aesthetics (required aesthetics are in bold):

  • x
  • ymax
  • ymin
  • alpha
  • colour
  • linetype
  • size
  • width

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)
Mapping a variable to y and also using stat="bin". With stat="bin", it will attempt to set the y value to the count of cases in each group. This can result in unexpected behavior and will not be allowed in a future version of ggplot2. If you want y to represent counts of cases, use stat="bin" and don't map a variable to y. If you want y to represent values in the data, use stat="identity". See ?geom_bar for examples. (Deprecated; last used in version 0.9.2)

p <- ggplot(df2, aes(fill=group, y=resp, x=trt)) p + geom_bar(position=dodge)
Mapping a variable to y and also using stat="bin". With stat="bin", it will attempt to set the y value to the count of cases in each group. This can result in unexpected behavior and will not be allowed in a future version of ggplot2. If you want y to represent counts of cases, use stat="bin" and don't map a variable to y. If you want y to represent values in the data, use stat="identity". See ?geom_bar for examples. (Deprecated; last used in version 0.9.2)

p + geom_bar(position=dodge) + geom_errorbar(limits, position=dodge, width=0.25)
Mapping a variable to y and also using stat="bin". With stat="bin", it will attempt to set the y value to the count of cases in each group. This can result in unexpected behavior and will not be allowed in a future version of ggplot2. If you want y to represent counts of cases, use stat="bin" and don't map a variable to y. If you want y to represent values in the data, use stat="identity". See ?geom_bar for examples. (Deprecated; last used in version 0.9.2)

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)

See also

geom_pointrange: range indicated by straight line, with point in the middle; geom_linerange: range indicated by straight line; geom_crossbar: hollow bar with middle indicated by horizontal line; stat_summary: examples of these guys in use, geom_smooth for continuous analog