scale_discrete

scale_x_discrete(name=NULL, expand=c(0.05, 0.55), limits=NULL, breaks=NULL, labels=NULL, formatter=identity, drop=FALSE, ...)
scale_y_discrete(name=NULL, expand=c(0.05, 0.55), limits=NULL, breaks=NULL, labels=NULL, formatter=identity, drop=FALSE, ...)
scale_z_discrete(name=NULL, expand=c(0.05, 0.55), limits=NULL, breaks=NULL, labels=NULL, formatter=identity, drop=FALSE, ...)

Discrete position scale

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

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Parameters

Parameters control the appearance of the scale. 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.

name: name of scale to appear in legend or on axis. Maybe be an expression: see ?plotmath
expand: numeric vector of length 2, giving multiplicative and additive expansion factors
limits: numeric vector of length 2, giving the extent of the scale
breaks: numeric vector indicating where breaks should lie
labels: character vector giving labels associated with breaks
formatter: NULL
drop: NULL

Returns

This function returns a scale object.

Examples

> qplot(cut, data=diamonds, stat="bin") 
  
> qplot(cut, data=diamonds, geom="bar") 
  
>  
> # The discrete position scale is added automatically whenever you 
> # have a discrete position. 
>  
> (d <- qplot(cut, clarity, data=subset(diamonds, carat > 1), geom="jitter")) 
  
>  
> d + scale_x_discrete("Cut") 
  
> d + scale_x_discrete("Cut", labels=c("F","G","VG","P","I")) 
  
>  
> d + scale_y_discrete("Clarity") 
  
> d + scale_x_discrete("Cut") + scale_y_discrete("Clarity") 
  
>  
> # Use limits to adjust the which levels (and in what order) 
> # are displayed 
> d + scale_x_discrete(limits=c("Fair","Ideal")) 
Warning: Removed 11189 rows containing missing values (geom_point).
  
>  
> # you can also use the short hand functions xlim and ylim 
> d + xlim("Fair","Ideal", "Good") 
Error: Continuous variable (cut) supplied to discrete scale_discrete.
  
> d + ylim("I1", "IF") 
Error: Continuous variable (clarity) supplied to discrete scale_discrete.
  
>  
> # See ?reorder to reorder based on the values of another variable 
> qplot(manufacturer, cty, data=mpg) 
  
> qplot(reorder(manufacturer, cty), cty, data=mpg) 
  
> qplot(reorder(manufacturer, displ), cty, data=mpg) 
  
>  
> # Use abbreviate as a formatter to reduce long names 
> qplot(reorder(manufacturer, cty), cty, data=mpg) + 
+   scale_x_discrete(formatter = "abbreviate")

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