gradientLegend: Add a gradient legend to a plot.

In plotfunctions: Various Functions to Facilitate Visualization of Data and Analysis

Description

Add a gradient legend to a contour plot (or other plot) to indicate the range of values represented by the color palette.

Usage

gradientLegend(
  valRange,
  color = "terrain",
  nCol = 30,
  pos = 0.875,
  side = 4,
  dec = NULL,
  length = 0.25,
  depth = 0.05,
  inside = FALSE,
  coords = FALSE,
  pos.num = NULL,
  n.seg = 1,
  border.col = "black",
  tick.col = NULL,
  fit.margin = TRUE,
  ...
)

Arguments

valRange	Range of the values that is represented by the color palette. Normally two value-vector. If a larger vector is provided, only the min and max values are being used.
color	Name of color palette to use ('topo', 'terrain', 'heat', 'rainbow'). Custom color palettes can also be provided, but then the argument nCol is ignored.
nCol	Number of colors in the color palette.
pos	A number indicating the position on the axis in proportion. Using the arguments length and depth and side the position of the legend is calculated automatically. Alternatively, one could provide a vector with 4 numbers, providing the xleft, ybottom, xright, ytop of a rectangle. These 4 points are indicated in proportions of the x- and y-axis. However, if the argument coords is set to TRUE, these positions are taken as values in the Cartesian coordinate system of the plot. Note: coords is only considered for 4-number vectors of pos.
side	Which axis to choose: 1=bottom, 2=left, 3=top, 4=right. Default is 4.
dec	Number of decimals for rounding the numbers, set to NULL on default (no rounding).
length	Number, indicating the width of the legend as proportion with respect to the axis indicated by side. Note: when pos is defined by 4 numbers, length is ignored.
depth	Number, indicating the height of the legend as proportion with respect to the axis perpendicular to side. Note: when pos is defined by 4 numbers, depth is ignored.
inside	Logical: whether or not to plot the legend inside or outside the plot area. Note: when pos is defined by 4 numbers, inside is ignored.
coords	Logical: whether or not pos (and optionally n.seg) is defined as coordinates. When FALSE, the default, pos is defined in proportions. Note: when pos is defined by 1 number, inside is ignored.
pos.num	Numeric value, indicating the position of the numbers with respect to the tick marks. 1=bottom, 2=left, 3=top, 4=right.
n.seg	Number of ticks and markers on the scale. Defaults to 1. If vector is provided instead of number, all numbers are considered as marker values on the scale provided by valRange.
border.col	Color of the border (if NA border is omitted).
tick.col	Color of the tick marks. Defaults to border.col value.
fit.margin	Logical: whether the labels of the gradient legend should be forced to fit in the margin or not.
...	Other parameters for the marker labels (see text).

Author(s)

Jacolien van Rij

See Also

Other Functions for plotting: addInterval(), add_bars(), add_n_points(), alphaPalette(), alpha(), check_normaldist(), color_contour(), dotplot_error(), drawDevArrows(), emptyPlot(), errorBars(), fill_area(), getCoords(), getFigCoords(), getProps(), legend_margin(), marginDensityPlot(), plot_error(), plot_image(), plotsurface(), sortBoxplot()

Examples

# empty plot:
emptyPlot(1,1, main='Test plot', axes=FALSE)
box()
# legend on outside of plotregion:
gradientLegend(valRange=c(-14,14), pos=.5, side=1)
gradientLegend(valRange=c(-14,14), pos=.5, side=2)
gradientLegend(valRange=c(-14,14), pos=.5, side=3)
gradientLegend(valRange=c(-14,14), pos=.5, side=4)

# legend on inside of plotregion:
gradientLegend(valRange=c(-14,14), pos=.5, side=1, inside=TRUE)
gradientLegend(valRange=c(-14,14), pos=.5, side=2, inside=TRUE)
gradientLegend(valRange=c(-14,14), pos=.5, side=3, inside=TRUE)
gradientLegend(valRange=c(-14,14), pos=.5, side=4, inside=TRUE)

# empty plot:
emptyPlot(1,1, main='Test plot', axes=FALSE)
box()
# number of segments:
gradientLegend(valRange=c(-14,14), n.seg=3, pos=.5, side=1)
gradientLegend(valRange=c(-14,14), n.seg=c(-3,5), pos=.5, side=1, 
    inside=TRUE)

# This produces a warning, as there is no space for labels here:
## Not run: 
    gradientLegend(valRange=c(-14.235,14.2), pos=.5, 
        n.seg = c(-7,0), side=4)

## End(Not run)
# different solutions:
# 1. adjust range (make sure also to adjust the range in the plot, 
#    for example by changing zlim)
emptyPlot(1,1, main='Test plot')
gradientLegend(valRange=c(-14,14), n.seg = c(-7,0), side=4)
# 2. reduce number of decimals:
emptyPlot(1,1, main='Test plot')
gradientLegend(valRange=c(-14.235,14.2), n.seg = c(-7,0), dec=1, side=4)
# 3. change labels to inside plot window:
emptyPlot(1,1, main='Test plot')
gradientLegend(valRange=c(-14.235,14.2), n.seg = c(-7,0), 
    dec=1, side=4, inside=TRUE)
# 4. increase right margin:
oldmar <- par()$mar
par(mar=c(5.1,3.1,4.1,4.1))
emptyPlot(1,1, main='Test plot')
gradientLegend(valRange=c(-14.235,14.2), dec=2, 
    n.seg = c(-7,0), side=4)
par(mar=oldmar) # return old values
# 5. change label position:
emptyPlot(1,1, main='Test plot')
gradientLegend(valRange=c(-14.235,14.2), dec=2, 
    n.seg = c(-7,0), side=4, pos.num=2)
gradientLegend(valRange=c(-14.235,14.2), dec=2, 
    n.seg = c(-7,0), side=4, pos.num=1, pos=.5)
# 6. change legend position and length:
emptyPlot(1,1, main='Test plot')
gradientLegend(valRange=c(-14.235,14.2), dec=2, 
    n.seg = c(-7,0), side=3, length=.5, pos=.75)

# change border color (and font color too!)
gradientLegend(valRange=c(-14,14),pos=.75, length=.5,
color=alphaPalette('white', f.seq=seq(0,1, by=.1)), 
border.col=alpha('gray'))

# when defining custom points, it is still important to specify side:

gradientLegend(valRange=c(-14,14), pos=c(.5,.25,.7,-.05), coords=TRUE, 
    border.col='red', side=1)
gradientLegend(valRange=c(-14,14), pos=c(.5,.25,.7,-.05), coords=TRUE, 
    border.col='red', side=2)

plotfunctions documentation built on April 28, 2020, 5:10 p.m.