HoldridgePlot() creates a blank triangular plot, as proposed by Holdridge (1947, 1967), onto which potential evapotranspiration (PET) ratio and annual precipitation data can be plotted (using the AddToHoldridge() family of functions) in order to interpret climatic life zones.

HoldridgePlot(
atip = NULL,
btip = NULL,
ctip = NULL,
alab = "Potential evapotranspiration ratio",
blab = "Annual precipitation / mm",
clab = "Humidity province",
lab.offset = 0.22,
lab.col = c("#D81B60", "#1E88E5", "#111111"),
xlim = NULL,
ylim = NULL,
lab.cex = 1,
lab.font = 0,
tip.cex = lab.cex,
tip.font = 2,
tip.col = "black",
isometric = TRUE,
atip.rotate = NULL,
btip.rotate = NULL,
ctip.rotate = NULL,
atip.pos = NULL,
btip.pos = NULL,
ctip.pos = NULL,
col = NA,
panel.first = NULL,
panel.last = NULL,
grid.lines = 8,
grid.col = c(NA, "#1E88E5", "#D81B60"),
grid.lty = "solid",
grid.lwd = par("lwd"),
grid.minor.lines = 0,
grid.minor.col = "lightgrey",
grid.minor.lty = "solid",
grid.minor.lwd = par("lwd"),
hex.border = "#888888",
hex.col = HoldridgeHypsometricCol,
hex.lty = "solid",
hex.lwd = par("lwd"),
hex.cex = 0.5,
hex.labels = NULL,
hex.font = NULL,
hex.text.col = "black",
axis.cex = 0.8,
axis.col = c(grid.col[2], grid.col[3], NA),
axis.font = par("font"),
axis.labels = TRUE,
axis.lty = "solid",
axis.lwd = 1,
axis.rotate = TRUE,
axis.pos = NULL,
axis.tick = TRUE,
ticks.lwd = axis.lwd,
ticks.length = 0.025,
ticks.col = grid.col,
...
)

HoldridgeBelts(
grid.col = "#004D40",
grid.lty = "dotted",
grid.lwd = par("lwd")
)

HoldridgeHexagons(
border = "#004D40",
hex.col = HoldridgeHypsometricCol,
lty = "dotted",
lwd = par("lwd"),
labels = NULL,
cex = 1,
text.col = NULL,
font = NULL
)

## Arguments

atip

Character string specifying text to title corners, proceeding clockwise from the corner specified in point (default: top).

btip

Character string specifying text to title corners, proceeding clockwise from the corner specified in point (default: top).

ctip

Character string specifying text to title corners, proceeding clockwise from the corner specified in point (default: top).

alab

Character string specifying text with which to label the corresponding sides of the triangle. Left or right-pointing arrows are produced by typing \\U2190 or \\U2192, or using expression('value' %->% '').

blab

Character string specifying text with which to label the corresponding sides of the triangle. Left or right-pointing arrows are produced by typing \\U2190 or \\U2192, or using expression('value' %->% '').

clab

Character string specifying text with which to label the corresponding sides of the triangle. Left or right-pointing arrows are produced by typing \\U2190 or \\U2192, or using expression('value' %->% '').

lab.offset

Numeric specifying distance between midpoint of axis label and the axis. Increase padding if labels are being clipped. Use a vector of length three to specify a different offset for each label.

lab.col

Character vector specifying colours for axis labels. Use a vector of length three to specify a different colour for each label.

xlim

Numeric vectors of length 2 specifying the minimum and maximum x and y limits of the plotted area, to which padding will be added. The default is to display the complete height or width of the plot. Allows cropping to magnified region of the plot. (See vignette for diagram.) May be overridden if isometric=TRUE; see documentation of isometric parameter.

ylim

Numeric vectors of length 2 specifying the minimum and maximum x and y limits of the plotted area, to which padding will be added. The default is to display the complete height or width of the plot. Allows cropping to magnified region of the plot. (See vignette for diagram.) May be overridden if isometric=TRUE; see documentation of isometric parameter.

lab.cex

Numeric specifying character expansion (font size) for axis labels. Use a vector of length three to specify a different value for each direction.

lab.font

Numeric specifying font style (Roman, bold, italic, bold-italic) for axis titles. Use a vector of length three to set a different font for each direction.

tip.cex

Numeric specifying character expansion (font size) for axis labels. Use a vector of length three to specify a different value for each direction.

tip.font

Numeric specifying font style (Roman, bold, italic, bold-italic) for axis titles. Use a vector of length three to set a different font for each direction.

tip.col

Colours for the axis line, tick marks and tip labels respectively. Use a vector of length three to set a different value for each direction. axis.col = NULL means to use par('fg'), possibly specified inline, and ticks.col = NULL means to use whatever colour axis.col resolved to.

isometric

Logical specifying whether to enforce an equilateral shape for the ternary plot. If only one of xlim and ylim is set, the other will be calculated to maintain an equilateral plot. If both xlim and ylim are set, but have different ranges, then the limit with the smaller range will be scaled until its range matches that of the other limit.

atip.rotate

Integer specifying number of degrees to rotate label of rightmost apex.

btip.rotate

Integer specifying number of degrees to rotate label of rightmost apex.

ctip.rotate

Integer specifying number of degrees to rotate label of rightmost apex.

atip.pos

Integer specifying positioning of labels, iff the corresponding xlab.rotate parameter is set.

btip.pos

Integer specifying positioning of labels, iff the corresponding xlab.rotate parameter is set.

ctip.pos

Integer specifying positioning of labels, iff the corresponding xlab.rotate parameter is set.

Numeric specifying size of internal margin of the plot; increase if axis labels are being clipped.

col

The colour for filling the plot; see polygon.

panel.first

An expression to be evaluated after the plot axes are set up but before any plotting takes place. This can be useful for drawing backgrounds, e.g. with ColourTernary() or HorizontalGrid(). Note that this works by lazy evaluation: passing this argument from other plot methods may well not work since it may be evaluated too early.

panel.last

An expression to be evaluated after plotting has taken place but before the axes and box are added. See the comments about panel.first.

grid.lines

Integer specifying the number of grid lines to plot.

grid.col

Colours to draw the grid lines. Use a vector of length three to set different values for each direction.

grid.lty

Character or integer vector; line type of the grid lines. Use a vector of length three to set different values for each direction.

grid.lwd

Non-negative numeric giving line width of the grid lines. Use a vector of length three to set different values for each direction.

grid.minor.lines

Integer specifying the number of minor (unlabelled) grid lines to plot between each major pair.

grid.minor.col

Colours to draw the grid lines. Use a vector of length three to set different values for each direction.

grid.minor.lty

Character or integer vector; line type of the grid lines. Use a vector of length three to set different values for each direction.

grid.minor.lwd

Non-negative numeric giving line width of the grid lines. Use a vector of length three to set different values for each direction.

hex.border, hex.lty, hex.lwd

Parameters to pass to HoldridgeHexagons(). Set to NA to suppress hexagons.

hex.col

Fill colour for hexagons. Provide a vector specifying a colour for each hexagon in turn, reading from left to right and top to bottom, or a function that accepts two arguments, numerics pet and prec, and returns a colour in a format accepted by polygon().

hex.cex, hex.font, hex.text.col

Parameters passed to text() to plot hex.labels.

hex.labels

38-element character vector specifying label for each hexagonal class, from top left to bottom right.

axis.cex

Numeric specifying character expansion (font size) for axis labels. Use a vector of length three to set a different value for each direction.

axis.col

Colours for the axis line, tick marks and tip labels respectively. Use a vector of length three to set a different value for each direction. axis.col = NULL means to use par('fg'), possibly specified inline, and ticks.col = NULL means to use whatever colour axis.col resolved to.

axis.font

Font for text. Defaults to par('font').

axis.labels

This can either be a logical value specifying whether (numerical) annotations are to be made at the tickmarks, or a character or expression vector of labels to be placed at the tick points.

axis.lty

Line type for both the axis line and tick marks. Use a vector of length three to set a different value for each direction.

axis.lwd

Line width for the axis line and tick marks. Zero or negative values will suppress the line or ticks. Use a vector of length three to set different values for each axis.

axis.rotate

Logical specifying whether to rotate axis labels to parallel grid lines, or numeric specifying custom rotation for each axis, to be passed as srt parameter to text(). Expand margins or set par(xpd = NA) if labels are clipped.

axis.pos

Vector of length one or three specifying position of axis labels, to be passed as pos parameter to text(); populated automatically if NULL (the default).

axis.tick

Logical specifying whether to mark the axes with tick marks.

ticks.lwd

Line width for the axis line and tick marks. Zero or negative values will suppress the line or ticks. Use a vector of length three to set different values for each axis.

ticks.length

Numeric specifying distance that ticks should extend beyond the plot margin. Also affects position of axis labels, which are plotted at the end of each tick. Use a vector of length three to set a different length for each direction.

ticks.col

Colours for the axis line, tick marks and tip labels respectively. Use a vector of length three to set a different value for each direction. axis.col = NULL means to use par('fg'), possibly specified inline, and ticks.col = NULL means to use whatever colour axis.col resolved to.

...

Additional parameters to plot.

border

Colour to use for hexagon borders.

lty, lwd, cex, font

Graphical parameters specifying properties of hexagons to be plotted.

labels

Vector specifying labels for life zone hexagons to be plotted. Suggested values: holdridgeClassesUp, holdridgeLifeZonesUp.

text.col

Colour of text to be printed in hexagons.

## Details

HoldridgePoints(), HoldridgeText() and related functions allow data points to be added to an existing plot; AddToHoldridge() allows plotting using any of the standard plotting functions.

HoldridgeBelts() and HoldridgeHexagons() plot interpretative lines and hexagons allowing plotted data to be linked to interpreted climate settings.

## References

Holdridge (1947), "Determination of world plant formations from simple climatic data", Science 105:367–368. doi:10.1126/science.105.2727.367

Holdridge (1967), Life zone ecology. Tropical Science Center, San José

Other Holdridge plotting functions: AddToHoldridge(), HoldridgeHypsometricCol(), holdridgeClasses, holdridge
data(holdridgeLifeZonesUp, package = "Ternary")