Soil Profile Sketches

Author

D.E. Beaudette

Published

March 27, 2025

Introduction

This is an expanded description of the arguments to plotSPC() and tips on making soil profile sketches look the way you want them to. Be sure to get the latest version of aqp.

Example Data

library(aqp)
library(soilDB)

# some interesting soil series
s <- c('leon', 'musick', 'clarksville', 'pardee', 'lucy', 'pierre', 'drummer', 'zook', 'san joaquin')

# get basic morphology and extended data from SoilWeb cache
osds.full <- fetchOSD(s, extended = TRUE)

# save copy of SoilProfileCollection for later
osds <- osds.full$SPC

Canvas

See the SPC introduction for the basics.

explainPlotSPC(osds)

Graphical explanation of arguments used to adjust the layout of soil profile sketches by plotSPC().

Arguments to `plotSPC`

Options can be used to conveniently specify sets of arguments that will be used in several calls to plotSPC() within a single R session. For example, arguments can be specified in a named list (.a) and set using: options(.aqp.plotSPC.args = .a). Reset these options via options(.aqp.plotSPC.args = NULL). Arguments explicitly passed to plotSPC() will override arguments set via options().

`x`

A SoilProfileCollection object with one or more profiles. Large collections (>25 profiles) may be hard to interpret on screen. Consider save the output directly to a PNG or PDF, for example:

# start output device, dimensions are in pixels
png(filename = 'output.png', width = 1600, height = 800)

# plot
plotSPC(reallyBigSPC)

# close device, write file
dev.off()

Turning off ID and horizon designation annotation is another strategy for getting a quick glimpse of a large collection. Turning off profile and horizon boundary outlines with divide.hz = FALSE can help too.

# a single profile from our example
musick <- subset(osds, id == 'MUSICK')

# standard deviation of horizon boundary variation
horizons(musick)$hzb <- 10

# simulate 50 profiles
musick.sim <- perturb(musick, n = 50, boundary.attr = 'hzb')

# no margins
par(mar = c(0, 0, 0, 0))
# note other arguments used to improve legibility
plotSPC(musick.sim, print.id = FALSE, name = NA, width = 0.4, divide.hz = FALSE, depth.axis = list(line = -4, cex = 1))

50 simulated variations of the Musick OSD pedon.

Profile Arrangement

n

A single integer describing the amount of space along x-axis to allocate, defaults to length(x).

explainPlotSPC(osds, cex.names = 0.66, width = 0.3, n = 15, print.id = FALSE, name.style = 'center-center')

text(x = 10.5, y = 90, label = "additional space allocated by 'n = 15'", adj = 0, cex = 0.75)
arrows(x0 = length(osds) + 1, x1 = 15, y0 = 100, y1 = 100, code = 3, length = 0.1)

A demonstration of the extra space allocated by adjusting the `n` argument.

plot.order

An integer vector describing the order in which soil profiles should be plotted. The ordering vector may contain duplicates, but may not include values outside the range of \([1, length(x)]\).

# integer labels encoding original order
site(osds)$original.order <- 1:length(osds)

# shuffle ordering vector 
idx  <- sample(osds$original.order)

# re-ordering index may contain duplicates
# idx <- rep(1:2, length.out = length(osds))


# setup margins, multi-figures
par(mar = c(0, 0, 2, 0), mfcol = c(1, 2))
plotSPC(osds, depth.axis = FALSE, label = 'original.order', name = NA, width = 0.35, cex.id = 1, max.depth = 175)
title('original order')

plotSPC(osds, depth.axis = FALSE, label = 'original.order', plot.order = idx, name = NA, width = 0.35, cex.id = 1, max.depth = 175)
title('new order')

A graphical demonstration of changing the profile plotting order as specified using an integer index.

relative.pos

vector of relative positions along the x-axis, within {1, n}, ignores plot.order see details

add

When TRUE, sketches and annotations (like a depth axis) are added to the current output device. With careful use of x.idx.offset it is possible to combine several sets of profiles, such as the results of a simulation (see perturb()). With careful use of scaling.factor, profiles can be added to any figure.

# select first profile
x <- osds[1, ]

# convert horizon distinctness codes 
# to a horizon boundary "variability" index
horizons(x)$hzd <- hzDistinctnessCodeToOffset(x$distinctness) * 2

# generate 10 simulations
x.sim <- perturb(x, n = 10, boundary.attr = 'hzd')

# margins
par(mar = c(0, 0, 0, 0))

# plot the source profile, leaving room for 11 profiles (n = 11)
plotSPC(x, cex.names = 0.66, name.style = 'center-center', width = 0.3, depth.axis = FALSE, hz.depths = TRUE, hz.depths.offset = 0.05, n = 11, id.style = 'side', cex.id = 0.66, fixLabelCollisions = TRUE, max.depth = 145)

# add 10 simulations, offset 1 position to the right with x.idx.offset = 1
plotSPC(x.sim, cex.names = 0.66, name.style = 'center-center', width = 0.3, depth.axis = FALSE, hz.depths = TRUE, hz.depths.offset = 0.05, print.id = FALSE, add = TRUE, x.idx.offset = 1, fixLabelCollisions = TRUE, max.depth = 145)

# annotate simulations
arrows(x0 = 2, x1 = 11, y0 = -15, y1 = -15, length = 0.1, code = 3)
mtext('Simulation', side = 3, at = 5.5, line = -2.5, font = 2, adj = 0)

x.idx.offset

Horizontal offset from 0 (left-hand edge), used to shift all profiles left or right within the sketch. Sometimes this is useful for making small, aesthetic adjustments especially when making sketches of large collections. When used together with the add argument, it is possible to align multiple versions of the same data by shifting profiles left or right. The following example adds profile sketches that use dry soil colors next to the original (moist soil colors) sketches.

# convert dry colors to hex notation
osds$dry_color <- munsell2rgb(osds$dry_hue, osds$dry_value, osds$dry_chroma)

# adjust margins
par(mar = c(1.5, 0, 2, 1))

# original data, supress horizon designations
plotSPC(osds, width = 0.2, name = NA)

# add and shift dry color sketches to the left (-0.4 units)
plotSPC(osds, width = 0.15, cex.names = 0.66, depth.axis = FALSE, print.id = FALSE, name = NA, x.idx.offset = -0.4, add = TRUE, color = 'dry_color')

# a title
title('Moist and Dry Colors')

# demonstrate shift with an arrow below each profile
s <- 1:length(osds)
bottoms <- profileApply(osds, max) + 15
arrows(x0 = s, y0 = bottoms, x1 = s - 0.4, y1 = bottoms, length = 0.1)

# annotate moist vs. dry
text(x = s, y = bottoms, labels = 'M', pos = 3, font = 3, cex = 0.66)
text(x = s - 0.4, y = bottoms, labels = 'D', pos = 3, font = 3, cex = 0.66)

y.offset

Either a single value or numeric vector of vertical offsets with length == length(x), in depth units of x. Profile sketches and depth axis are shifted when using a single y offset value. The depth axis is disabled when using multiple y offsets. Note: y.offset is automatically re-ordered by plot.order.

Shift all profile sketches down 300cm, leaving room for additional annotation above. Right-hand axis added for clarity.

par(mar = c(0, 0, 0, 0))

plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.3, y.offset = 300, hz.depths = TRUE, fixLabelCollisions = TRUE, hz.depths.offset = 0.05, depth.axis = FALSE)

# fake data
rect(xleft = (1:length(osds)) - 0.25, xright = (1:length(osds)) + 0.25, ybottom = 250, ytop = runif(n = length(osds), min = 0, max = 250), col = 4)

# demonstrate full y-range within figure
axis(side = 4, line = -3, las = 1)

Shift each profile sketch a different amount. Transect or cross-section figures can be manually created in this way. See also scaling.factor for applying a vertical scaling to all profiles.

# manually create a nice looking set of relative elevations along a pretend landform
.yshift <- c(0, 1, 4, 8, 15, 22, 30, 35, 40) * 5

# compute the Hurst Redness Index for each horizon
# this is a horizon-level attribute
osds$hr <- hurst.redness(osds$hue, osds$value, osds$chroma)

# compute the profile median of Hurst Redness Index
# this is now a site-level attribute
osds$profile.median.hr <- profileApply(osds, function(i) median(i$hr, na.rm = TRUE))

# rank profile median, Hurst Redness Index
# use this to sort profiles
o <- order(osds$profile.median.hr)

# however, this will complicate a manual specification of the landform surface
# now we need an index back to the original order
idx <- match(1:length(osds), o)

# margins
par(mar = c(0, 0, 0, 0))

# apply profile-specific y-offsets
# re-arrange horizontal position with 'plot.order = o'
plotSPC(osds, cex.id = 0.66, cex.names = 0.66, name.style = 'center-center', width = 0.3, y.offset = .yshift[idx], hz.depths = TRUE, fixLabelCollisions = TRUE, hz.depths.offset = 0.05, plot.order = o)

# demonstrate full y-range within figure
axis(side = 4, line = -3, las = 1)

# add idealized land surface
.xland <- 1:length(osds)
.yland <- .yshift - 30

# smooth via interpolation
.landSurface <- splinefun(.xland, .yland)
.s <- seq(0.5, length(osds) + 0.5, by = 0.1)

# add smoothed, idealized land surface
lines(x = .s, y = .landSurface(.s), lwd = 2)

# remind ourselves that this is fake
title('A Fake Diagram of Real Soils', line= -1.5)

Profile Styling

max.depth

Set the maximum depth for soil profile sketches, given in the same units as used by the SoilProfileCollection. Profiles deeper than max.depth are truncated and marked with a “ragged” bottom boundary. Values deeper than the deepest profiles in the collection (e.g. max(x)) will extend the vertical dimension of the sketch to max.depth. This can be a handy way to include extra space below profile sketches for additional annotation.

par(mar = c(1, 0, 0, 1))

plotSPC(osds, cex.names = 0.66, name = NA, max.depth = 145)

# SPC truncated at 145cm
abline(h = 145, lty = 2)

width

Each profile is given 1 horizontal unit of space in the figure. The width argument is given as 1/2 of this space: typically ranging from 0.1–0.4. Values >= 0.5 will cause overlap.

par(mar = c(0, 0, 0, 1))

plotSPC(osds, cex.names = 0.66, print.id = FALSE, name = NA)

# annotate horizontal space allocated to each profile
abline(v = seq(0.5, length(osds) + 0.5, by = 1), lty = 2)

par(mar = c(0, 0, 0, 1))

# too skinny, but lots of room for extra annotation
plotSPC(osds, width = 0.1, cex.names = 0.66, print.id = FALSE)

# works OK without horizon designations on the right side
plotSPC(osds, width = 0.45, cex.names = 0.66, name = NA)

# about right
plotSPC(osds, width = 0.3, cex.names = 0.66)

scaling.factor

vertical scaling of profile depths, useful for adding profiles to an existing figure

# margins
par(mar = c(0, 0, 0, 0))

# plot the source profile, leaving room for 11 profiles (n = 11)
plotSPC(osds, cex.names = 0.66, name = NA, width = 0.25, depth.axis = FALSE, hz.depths = TRUE, n = length(osds) * 2, print.id = FALSE, fixLabelCollisions = TRUE, hz.depths.offset = 0.05)

plotSPC(osds, cex.names = 0.66, name = NA, width = 0.25, depth.axis = FALSE, hz.depths = TRUE, print.id = FALSE, add = TRUE, x.idx.offset = length(osds), scaling.factor = 0.5, fixLabelCollisions = TRUE, hz.depths.offset = 0.05)

arrows(x0 = length(osds) + 1, x1 = length(osds) * 2, y0 = -15, y1 = -15, length = 0.1, code = 3)
mtext('scaling.factor = 0.5', side = 3, at = 12.5, line = -2.25, font = 2, adj = 0, cex = 0.85)

lwd

line width multiplier used for sketches

par(mar = c(0, 0, 0, 1))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.3, lwd = 2, color = NA, name = NA)

lty

line style used for all sketches

par(mar = c(0, 0, 0, 1))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.3, lty = 2, color = NA, name = NA)

Horizon Styling

color

A quoted column name containing R-compatible color descriptions (e.g. #7A5C37FF, approximately 10YR 4/4), or numeric / categorical data to be displayed thematically.

Numeric values.

# leave room at the top for a legend, and on the right hand side for depth axis.
par(mar = c(0, 0, 3, 1))

# horizon top depth
plotSPC(osds, color = 'top', col.label = 'Horizon Top Depth (cm)', cex.names = 0.66)

plotSPC(osds, color = 'value', col.label = 'Munsell Value (moist)', cex.names = 0.66)

Categorical values.

# set ordering of Munsell hue according to hue position
osds$hue_ordered <- factor(osds$hue, levels = huePosition(returnHues = TRUE))

# leave room at the top for a legend, and on the right hand side for depth axis.
par(mar = c(0, 0, 3, 1))

plotSPC(osds, color = 'hue_ordered', col.label = 'Munsell Value (moist)', cex.names = 0.66)

# reaction class is already an ordered factor, set in fetchOSD()
plotSPC(osds, color = 'pH_class', col.label = 'Reaction Class', cex.names = 0.66, col.legend.cex = 0.66)

User-defined colors in hex notation.

# assign each horizon a color of the rainbow
horizons(osds)$rainbowColors <- rainbow(n = nrow(osds))

par(mar = c(0, 0, 0, 0))
plotSPC(osds, color = 'rainbowColors', cex.names = 0.66, col.legend.cex = 0.66)

# color gradient from 2.5YR 6/8 -> 5Y 3/3
cr <- colorRampPalette(parseMunsell(c('2.5YR 6/8', '5Y 3/3')), space = 'Lab', interpolate = 'spline')

horizons(osds)$gradientColors <- cr(n = nrow(osds))

plotSPC(osds, color = 'gradientColors', cex.names = 0.66, col.legend.cex = 0.66)

density

fill density used for horizon color shading, either a single integer or a quoted column name (horizon-level attribute) containing integer values (default is NULL, no shading)

# make an index for shading density, based on horizon mid-points
# rescale slightly with power transform
osds$density.shading <- round(((osds$bottom + osds$top) / 2)^0.9)

par(mar = c(0, 0, 0, 1))
plotSPC(osds, cex.names = 0.66, density = 'density.shading')

show.legend

logical, show legend? (default is TRUE)

col.label

thematic legend title

col.palette

color palette used for thematic sketches (default is rev(brewer.pal(10, 'Spectral')))

col.palette.bias

color ramp bias (skew), see colorRamp

col.legend.cex

scaling of thematic legend

n.legend

approximate number of classes used in numeric legend, max number of items per row in categorical legend

default.color

default horizon fill color used when color attribute is NA. This can be a useful setting when highlighting horizons that are missing data or colors.

# remove some colors at random
osds$soil_color.NA <- osds$soil_color
osds$soil_color.NA[sample(1:nrow(osds), size = 5)] <- NA

par(mar = c(0, 0, 0, 1))
plotSPC(osds, cex.names = 0.66, color = 'soil_color.NA', default.color = 'yellow')

Annotation / Labeling

name

Quoted column name of the (horizon-level) attribute containing horizon designations or labels, if missing hzdesgnname(x) is used. Suppress horizon name printing by setting name = NA or name = ''.

name.style

Horizon designation label style, one of c('right-center', 'center-center', 'left-center', 'left-top', 'center-top')). The right-center position has been the default in aqp since 2010. I prefer the center-center style. Note that horizon designation label colors are automatically adjusted for maximum contrast (by invertLabelColor()) when placed inside of a profile sketch.

par(mar=c(0,0,1,0), mfcol=c(5,1))

for(i in c('right-center', 'center-center', 'left-center', 'left-top', 'center-top')) {
  plotSPC(osds, width = 0.33, cex.names = 0.9, shrink=TRUE, print.id = FALSE, plot.depth.axis=FALSE, name.style=i)
  mtext(text = i, at = 0.5, side=1, line=-4, cex=1, adj = 0, font = 2)
}

shrink

logical, reduce character scaling for ‘long’ horizon by 80%

shrink.cutoff

character length defining ‘long’ horizon names

shrink.thin

integer, horizon thickness threshold for shrinking horizon names by 80%, only activated when shrink = TRUE (NULL = no shrinkage)

abbr

logical, abbreviate label

abbr.cutoff

suggested minimum length for abbreviated label

label

A single (quoted) site-level attribute name that will be used to label profiles. This defaults to idname(x) (e.g. the profile ID), but can be anything in site(x). See id.style argument for adjusting side vs. top vs. automatic label positioning. Suppress printing of profile labels with print.id = FALSE.

par(mar = c(0, 0, 0, 1))
plotSPC(osds, cex.names = 0.66, label = 'subgroup', name.style = 'center-center', width = 0.3)
title('Subgroup Labels', line = -1)

hz.depths

When TRUE, small horizon depth labels are placed just to the right of horizon top depths (right justified). The results may be illegible if there are too many profiles in the collection or if profiles are too wide. Works best with name.style = 'center-center' and depth.axis = FALSE.

par(mar = c(0, 0, 0, 0))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.3, depth.axis = FALSE, hz.depths = TRUE)

hz.depths.offset

Numeric values between 0.01–0.15 shift horizon depth annotation to the right of profile sketches.

par(mar = c(0, 0, 0, 0))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.3, depth.axis = FALSE, hz.depths = TRUE, hz.depths.offset = 0.05)

hz.depths.lines

When TRUE, segments are drawn between horizon depth labels and actual horizon depth; this is useful when including horizon boundary distinctness and/or when fixLabelCollisions = TRUE.

par(mar = c(0, 0, 0, 0))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.3, depth.axis = FALSE, hz.depths = TRUE, hz.depths.offset = 0.05, hz.depths.lines = TRUE)

fixLabelCollisions

When TRUE, use aqp::fixOverlap() to attempt fixing horizon depth labeling collisions. This will slow plotting of large collections. Enabling fixes also sets hz.depths.lines = TRUE. A simulation of electrostatic charges is used to iteratively adjust labels until there is no overlap. See ?electroStatics_1D for details.

par(mar = c(0, 0, 0, 0))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.3, depth.axis = FALSE, hz.depths = TRUE, hz.depths.offset = 0.05, fixLabelCollisions = TRUE)

fixOverlapArgs

Pass additional arguments to fixOverlap() as a list. Fix overlapping labels with simulated annealing. Adjustments made by this method involve random permutations, so output is different each time. Use set.seed when you need consistent results. See ?SANN_1D for details.

par(mar = c(0, 0, 0, 0))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.3, depth.axis = FALSE, hz.depths = TRUE, hz.depths.offset = 0.05, fixLabelCollisions = TRUE, fixOverlapArgs = list(method = 'S'))

alt.label and alt.label.col

A single (quoted) site-level attribute name that will be used as secondary annotation, inset just below the top of each profile. Note that the alt.label.col argument will probably have to be used for legibility.

par(mar = c(0, 0, 0, 1))
plotSPC(osds, cex.names = 0.66, alt.label = 'tax_tempcl', width = 0.3, alt.label.col = 'white')

cex.names

This is a baseline scaling factor applied to all labels in the figure: ID labels, horizon designations, horizon depths, and depth axis. Values around 0.6 are usually just about right.

cex.id

Scaling factor applied to the profile IDs.

font.id

Font style applied to the profile IDs, default is 2 (bold).

id.style

Profile ID annotation style. The default value of auto uses a simple heuristic used to select from:

top: centered above each profile
side: along the top-left edge of profiles

Horizon Boundaries

raggedBottom

A quoted column name of the (site-level) attribute (logical) used to mark profiles with a truncated lower boundary. This type of annotation is a convenient way to demonstrate that soil, paralithic material, or bedrock contact likely extends below the depth of excavation.

par(mar = c(0, 0, 0, 1))

# flag all profiles as being incomplete / truncated
site(osds)$rb <- TRUE

plotSPC(osds, cex.names = 0.66, raggedBottom = 'rb', width = 0.33, name.style = 'center-center')

# flag some profiles as being incomplete / truncated
site(osds)$rb <- c(TRUE, FALSE, FALSE)

plotSPC(osds, cex.names = 0.66, raggedBottom = 'rb', width = 0.33, name.style = 'center-center')

A ragged bottom boundary is automatically added when max.depth < max(x). Suppress this behavior by setting raggedBottom = FALSE.

divide.hz

logical, divide horizons with line segment? (TRUE). Often handy when plotting a very large collection or for a artistic flair. PNG or similar graphics devices are suggested when setting divide.hz = FALSE.

# suppress printing of horizon designation
par(mar = c(0, 0, 0, 1))
plotSPC(osds, name = NA, name.style = 'center-center', divide.hz = FALSE, width = 0.33)

hz.distinctness.offset

NULL, or quoted column name (horizon-level attribute) containing vertical offsets used to depict horizon boundary distinctness (same units as profiles). Data from fetchOSD() contain these offsets in the hzd horizon-level attribute. See Visualization of Horizon Boundaries for details.

# use offset values instead of horizon designations to emphasize effect
par(mar = c(0, 0, 0, 1))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.33, hz.distinctness.offset = 'hzd', name = 'hzd')

hz.topography.offset

NULL, or quoted column name (horizon-level attribute) containing offsets used to depict horizon boundary topography. See Visualization of Horizon Boundaries for details.

# encode horizon boundary topography via vertical offset
osds$hzto <- hzTopographyCodeToOffset(osds$topography)

par(mar = c(0, 0, 0, 1))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.33, hz.topography.offset = 'hzto')

hz.boundary.lty

quoted column name (horizon-level attribute) containing line style (integers) used to encode horizon topography. See Visualization of Horizon Boundaries for details.

# encode horizon boundary topography as line type
osds$hzto.lty <- hzTopographyCodeToLineType(osds$topography)

par(mar = c(0, 0, 0, 1))
plotSPC(osds, cex.names = 0.66, name.style = 'center-center', width = 0.33, hz.topography.offset = 'hzto', hz.boundary.lty = 'hzto.lty')

Depth Axis

The depth axis is controlled via depth.axis argument as of aqp 2.0. The depth.axis argument can take two forms:

logical: FALSE (suppress the depth axis) or TRUE (use the default depth axis style)
a list with named elements: specify some or all of the depth axis parameters

Depth axis parameters include:

style: legend style, either ‘traditional’ (aqp 1.x default), ‘compact’, or ‘tape’
line: horizontal positioning, default is -2
cex: scaling factor for entire axis
interval: depth axis interval

As of aqp 2.x, the depth axis is truncated near max.depth.

par(mar = c(0, 0, 0, 4))
plotSPC(
  osds, 
  cex.names = 0.6, 
  name.style = 'center-center', 
  width = 0.3, 
  depth.axis = list(cex = 0.75, line = -1.5, interval = 15),
  max.depth = 225
  )

Backwards compatibility for aqp 1.x-style arguments is provided but a message is printed whenever the following arguments are used: cex.depth.axis, axis.line.offset, plot.depth.axis. These arguments will eventually be removed from plotSPC().

If you like the depth axis as used in aqp 1.x, set depth.axis = list(style = 'traditional'), or for all subsequent plots: options(.aqp.plotSPC.args = list(style = 'traditional'))

Secondary Annotation

addBracket()

Add vertical brackets next to profile sketches, smart enough follow ordering adjusted with plot.order and plot.order and relative.pos.

par(mar = c(0, 0, 0, 1))

# random ordering of profiles
plotSPC(
  osds, 
  cex.names = 0.66, 
  name.style = 'center-center', 
  width = 0.33, 
  plot.order = sample(1:length(osds))
)

# data.frame with profile IDs, 
# bracket top, bottom, and optional label
.brackets <- data.frame(
  id = profile_id(osds),
  top = minDepthOf(osds, pattern = 'B', na.rm = FALSE)$top,
  bottom = maxDepthOf(osds, pattern = 'B', top = FALSE)$bottom,
  label = 'label here'
)

# annotate "B" horizons
addBracket(.brackets, offset = - 0.45)

addVolumeFraction()

Approximation of volumetric data, such as rock fragments.

par(mar = c(0, 0, 0, 1))

plotSPC(
  osds, 
  cex.names = 0.66, 
  name = NA,
  name.style = 'center-center', 
  width = 0.33
)

# positive CIELAB A-coordinates
osds$A.coord <- pmax(0, munsell2rgb(osds$hue, osds$value, osds$chroma, returnLAB = TRUE)$A)

# interpret positive A-coordinates
# as percentages
addVolumeFraction(osds, colname = 'A.coord', col = 'white')

addDiagnosticBracket()

Sketch Metadata

Sometimes you need details from a sketch for further annotation; profile ordering, depth scaling, y-offsets, and so on. This information is stored in a special environment.

# re-order by max profile depth
# note this is not the same as soil depth (e.g. to contact)

# compute bottom-most horizon depth
.depths <- profileApply(osds, max)

# or, use [-style indexing and keywords
# "last horizon of each profile" and "bottom depth"
.depths <- osds[, , .LAST, .BOTTOM]

# shallow -> deep ordering
.order <- order(.depths)

# make a sketch
par(mar = c(0, 0, 0, 3))
plotSPC(osds, cex.names = 0.6, name.style = 'center-center', width = 0.3, plot.order = .order)

# get last sketch metadata
lastPP <- get("last_spc_plot", envir = aqp.env)
str(lastPP)

List of 16
 $ width         : num 0.3
 $ plot.order    : int [1:9] 6 1 2 8 4 7 9 3 5
 $ x0            : num [1:9] 1 2 3 4 5 6 7 8 9
 $ pIDs          : chr [1:9] "PARDEE" "CLARKSVILLE" "DRUMMER" "SAN JOAQUIN" ...
 $ idname        : chr "id"
 $ y.offset      : num [1:9] 0 0 0 0 0 0 0 0 0
 $ scaling.factor: num 1
 $ max.depth     : int 295
 $ n             : int 9
 $ xlim          : num [1:2] 0.6 9.9
 $ ylim          : num [1:2] 295 -15
 $ extra_x_space : num 0.9
 $ extra_y_space : num 15
 $ hz.depth.LAI  : num [1:9] NA NA NA NA NA NA NA NA NA
 $ legend.colors : chr [1:65] "#3E2B24FF" "#6E5E4BFF" "#AE9068FF" "#AE9068FF" ...
 $ legend.data   : NULL

# use plot order (from metadata) to annotate
text(
  x = seq_along(osds), 
  y = .depths[lastPP$plot.order] + 5, 
  labels = .depths[lastPP$plot.order], 
  cex = 0.55
)

This document is based on aqp version 2.2.