alignTransect: Calculate Relative Positions from Transect Data

In aqp: Algorithms for Quantitative Pedology

Calculate Relative Positions from Transect Data

Description

This function is used to support relative positioning of soil profiles by plotSPC, based on transect or gradient values typically associated with a site level attribute (e.g. elevation). Gradient values specified in x are translated to the range used by plotSPC (usually ⁠1, length(SPC)⁠) specified in x.min and x.max.

Usage

alignTransect(x, x.min, x.max, fix = TRUE, ...)

Arguments

x	numeric vector, describing values along a transect: distance, elevation, climatic variables, etc.. Typically sourced from the site level attributes of a SoilProfileCollection object. Order is not important.
x.min	numeric, lower boundary to relative position scale
x.max	numeric, upper boundary to relative position scale
fix	logical, attempt fixing overlapping positions with fixOverlap
...	additional arguments to fixOverlap

Details

See the Pair-Wise Distances by Generalized Horizon Labels tutorial for additional examples.

Value

list containing:

• grad: values of x in ascending order

• order: ordering vector of x

• relative.pos: elements of x translated to the new relative scale defined by x.min and x.max

Examples

data("sierraTransect")

# split transects
g <- subset(sierraTransect, transect == 'Granite')
a <- subset(sierraTransect, transect == 'Andesite')

g.p <- alignTransect(g$elev, x.min = 1, x.max = length(g), fix = FALSE)
a.p <- alignTransect(a$elev, x.min = 1, x.max = length(a), fix = FALSE)

op <- par(mar=c(2,0,0,2), mfrow=c(2,1))

plotSPC(g, width=0.25, name.style='center-center', 
        cex.names=0.75, 
        relative.pos = g.p$relative.pos, plot.order = g.p$order)

axis(1, at = g.p$relative.pos, labels = g.p$grad, line = -1.5)

plotSPC(a, width=0.25, name.style='center-center', 
        cex.names=0.75, 
        relative.pos = a.p$relative.pos, plot.order = a.p$order)

axis(1, at = a.p$relative.pos, labels = a.p$grad, line = -1.5)


par(op)

aqp documentation built on Oct. 19, 2024, 5:06 p.m.