R: Legend Gradient

legend.gradient {SDMTools} | R Documentation

## Legend Gradient

### Description

`legend.gradient` creates and displays a gradient legend on a plot or image file. The place and size of the legend is defined by coordinates, previously identified.

### Usage

    legend.gradient(pnts, cols = heat.colors(100), limits = c(0, 1),
      title = "Legend", ...)

### Arguments

`pnts` | x and y coordinates of the gradient location in the plot
`cols` | a set of 2 or more colors used in the image, to create the gradient
`limits` | to label the min and max values of the gradient in the legend
`title` | to specify the title of the legend
`...` | other graphical parameters defined by image() or plot()

### Value

nothing is returned, a gradient legend is added to a plot or a image.

### Author(s)

Lorena Falconi lorefalconi@gmail.com

### Examples

    #define a simple binary matrix
    tmat = { matrix(c( 0,0,0,1,0,0,1,1,0,1,
                       0,0,1,0,1,0,0,0,0,0,
                       0,1,NA,1,0,1,0,0,0,1,
                       1,0,1,1,1,0,1,0,0,1,
                       0,1,0,1,0,1,0,0,0,1,
                       0,0,1,0,1,0,0,1,1,0,
                       1,0,0,1,0,0,1,0,0,0,
                       0,1,0,0,0,1,0,NA,NA,NA,
                       0,0,1,1,1,0,0,NA,NA,NA,
                       1,1,1,0,0,0,0,NA,NA,NA),nr=10,byrow=TRUE) }

    #do the connected component labeling
    tasc = ConnCompLabel(tmat)

    # Create a color ramp
    colormap=c("grey","yellow","yellowgreen","olivedrab1","lightblue4")

    #create an image
    image(tasc,col=colormap, axes=FALSE, xlab="", ylab="", ann=FALSE)

    #points for the gradient legend
    pnts = cbind(x =c(0.8,0.9,0.9,0.8), y =c(1.0,1.0,0.8,0.8))

    #create the gradient legend
    legend.gradient(pnts,colormap,c("Low","High"))

[Package SDMTools version 1.1-221.2 Index]