SoilProfileCollection wrapper for mpspline2::mpspline()

Generate mass-preserving splines for any numeric attribute in a SoilProfileCollection using mpspline2::mpspline(). mpspline2 implements the method described in Bishop et al. (1999).

Usage

# S4 method for class 'SoilProfileCollection'
spc2mpspline(
  object,
  var_name = NULL,
  method = c("est_1cm", "est_icm", "est_dcm"),
  pattern = "R|Cr|Cd|m",
  hzdesgn = NULL,
  ...
)

Arguments

object

A SoilProfileCollection

var_name

Column name(s) in @horizons slot of object containing numeric values to spline

method

Options include "est_1cm" (default; 1cm estimates), "est_icm" (estimates over original layer boundaries), "est_dcm" (estimates over constant interval, specified with d argument to mpspline3::mpspline()). Default value for d is c(0, 5, 15, 30, 60, 100, 200).

pattern

Regex pattern to match for bottom of profile (passed to minDepthOf()) default: "R|Cr|Cd|m"; only used if hzdesgn is specified

hzdesgn

Column name in @horizons slot of object containing horizon designations default: NULL

...

Additional arguments to mpspline2::mpspline()

Value

A SoilProfileCollection with 1cm slices. Spline variables are in columns prefixed with "spline_" and RMSE/RMSE_IQR are in columns prefixed with "rmse_". If any profiles were removed from the collection, their profile IDs are stored in attr(result, 'removed').

Details

This function now relies on the missing data checks provided by the mpspline2 package. See attr(..., 'removed') to see whole profiles that were removed from the set. Horizons containing NA in the property of interest are dropped with a message.

Data completeness is assessed and the input SoilProfileCollection is filtered and truncated to create a container for the results from mpspline2::mpspline().

References

Bishop, T.F.A., McBratney, A.B., Laslett, G.M. (1999) Modelling soil attribute depth functions with equal-area quadratic smoothing splines. Geoderma 91(1–2), pp. 27-45. doi:10.1016/S0016-7061(99)00003-8

O'Brien, Lauren (2025). mpspline2: Mass-Preserving Spline Functions for Soil Data. R package version 0.1.9. https://cran.r-project.org/package=mpspline2

Author

Andrew G. Brown

Examples

data(sp1)
depths(sp1) <- id ~ top + bottom
hzdesgnname(sp1) <- "name"
  
# run on a single variable
res <- spc2mpspline(sp1, "prop")
  
# plot single-variable result
plotSPC(res[1:5, ], color = "prop_spline", divide.hz = FALSE)

# add a second continuous numeric variable for demonstration
sp1$value2 <- runif(nrow(horizons(sp1)))
  
# run on multiple variables
res2 <- spc2mpspline(sp1, c("prop", "value2"))
  
# plot multi-variable result
plotSPC(res2[1:5, ], color = "value2_spline", divide.hz = FALSE)

  
# run on multiple variables with custom depth intervals
res3 <- spc2mpspline(sp1,
                     c("prop", "value2"),
                     method = "est_dcm",
                     d = c(0, 10, 20, 50, 100))
plotSPC(res3[1:5, ], color = "value2_spline", divide.hz = FALSE)