aqp (version 1.7-7)

texture.triangle.low.rv.high: Soil Texture Low-RV-High as Defined by Quantiles

Description

This function accepts soil texture components (sand, silt, and clay percentages) and plots a soil texture triangle with a "representative value" (point) and low-high region (polygon) defined by quantiles. Marginal quantiles of sand, silt, and clay are used to define the boundary of a low-high region that encloses a severall likely soil texture classes based on the values in ssc. The defualt settings place the RV symbol at the texture defined by marginal medians of sand, silt, and clay. The default low-high region is defined by the 5th and 95th marginal percentiles of sand, silt, and clay.

Usage

texture.triangle.low.rv.high(ssc, p = c(0.05, 0.5, 0.95), 
method = c("approx", "closest"), n.closest = 3, delta = 1, 
pop.rv.col = "red", range.col = "RoyalBlue", range.alpha = 75)

Arguments

ssc

a matrix-like object with columns: 'sand', 'silt', 'clay', values are percentages that should add to 100.

p

percentiles defining 'low', 'representative value', and 'high'

method

'approximate' uses marginal quantiles of [sand, silt, clay], 'closest' uses those data points that are closest to the marginal quantiles

n.closest

for method='closest', the number of observations used to define the low-high region

delta

step-size used to form low-high region via 'approx' method

pop.rv.col

the symbol color used to denote the population representative value on the texture triangle

range.col

color of the polygon enclosing the low-high region

range.alpha

transparency of the low-high range polygon (0-255)

Value

• A high-level plot as generated by soil.texture.

See Also

triax.points, soil.texture

Examples

# sample data
data(loafercreek, package='soilDB')

# extract sand, silt, clay proportions
x <- na.omit(data.frame(sand=loafercreek$sand, silt=loafercreek$silt, clay=loafercreek$clay))

# test out the function
texture.triangle.low.rv.high(x, p=c(0.05, 0.5, 0.95))
texture.triangle.low.rv.high(x, p=c(0.25, 0.5, 0.75), range.col='darkgreen')

texture.triangle.low.rv.high(x, p=c(0.05, 0.5, 0.95), method='closest')
texture.triangle.low.rv.high(x, p=c(0.25, 0.5, 0.75), method='closest', range.col='darkgreen')