scale_gradientn

scale_colour_gradientn(name=NULL, colours, values=NULL, rescale=TRUE, space="rgb", breaks=NULL, labels=NULL, limits=NULL, trans="identity", ...)
scale_fill_gradientn(name=NULL, colours, values=NULL, rescale=TRUE, space="rgb", breaks=NULL, labels=NULL, limits=NULL, trans="identity", ...)

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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
• colours: NULL
• values: NULL
• rescale: NULL
• space: colour space to interpolate through, rgb or Lab, see ?colorRamp for details
• breaks: numeric vector indicating where breaks should lie
• labels: character vector giving labels associated with breaks
• limits: numeric vector of length 2, giving the extent of the scale
• trans: a transformer to use
• ...: other arguments

Returns

This function returns a scale object.

See also

• scale_gradient: continuous colour scale with midpoint
• colorRamp: for details of interpolation algorithm

Examples

> # scale_colour_gradient make it easy to use existing colour palettes 
>  
> dsub <- subset(diamonds, x > 5 & x < 6 & y > 5 & y < 6) 
> dsub$diff <- with(dsub, sqrt(abs(x-y))* sign(x-y)) 
> (d <- qplot(x, y, data=dsub, colour=diff)) 
  
>  
> d + scale_colour_gradientn(colour = rainbow(7)) 
  
> breaks <- c(-0.5, 0, 0.5) 
> d + scale_colour_gradientn(colour = rainbow(7), 
+   breaks = breaks, labels = format(breaks)) 
  
>  
> d + scale_colour_gradientn(colour = topo.colors(10)) 
  
> d + scale_colour_gradientn(colour = terrain.colors(10)) 
  
>  
> # You can force them to be symmetric by supplying a vector of 
> # values, and turning rescaling off 
> max_val <- max(abs(dsub$diff)) 
> values <- seq(-max_val, max_val, length = 11) 
>  
> d + scale_colour_gradientn(colours = topo.colors(10), 
+   values = values, rescale = FALSE) 
  
> d + scale_colour_gradientn(colours = terrain.colors(10), 
+   values = values, rescale = FALSE) 
  
>  

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© Hadley Wickham 2012