alignTransect: Calculate Relative Positions from Transect Data In aqp: Algorithms for Quantitative Pedology

 alignTransect R Documentation

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 May 29, 2024, 2:24 a.m.