mpspline2 (version 0.1.9)

mpspline: Spline discrete soils data - multiple sites

Description

This function implements the mass-preserving spline method of Bishop et al (1999) (tools:::Rd_expr_doi("10.1016/S0016-7061(99)00003-8")) for interpolating between measured soil attributes down a soil profile, across multiple sites' worth of data.

Usage

mpspline(
  obj = NULL,
  var_name = NULL,
  lam = 0.1,
  d = c(0, 5, 15, 30, 60, 100, 200),
  vlow = 0,
  vhigh = 1000
)

Value

A nested list of data for each input site. List elements are: Site ID, vector of predicted values over input intervals, vector of predicted values for each cm down the profile to max(d), vector of predicted values over d (output) intervals, and root mean squared error.

Arguments

obj

data.frame or matrix. Column 1 must contain site identifiers. Columns 2 and 3 must contain upper and lower sample depths, respectively. Subsequent columns will contain measured values for those depths.

var_name

character or integer vector denoting the column(s) in obj in which target data is stored. If not supplied, the fourth column of the input object is assumed to contain the target data.

lam

number; smoothing parameter for spline. Defaults to 0.1.

d

sequential integer vector; denotes the output depth ranges in cm. Defaults to c(0, 5, 15, 30, 60, 100, 200) after the GlobalSoilMap specification, giving output predictions over intervals 0-5cm, 5-15cm, etc.

vlow

numeric; constrains the minimum predicted value to a realistic number. Defaults to 0.

vhigh

numeric; constrains the maximum predicted value to a realistic number. Defaults to 1000.

Examples

# single variable
dat <- data.frame("SID" = c( 1,  1,  1,  1,   2,   2,   2,   2),
                   "UD" = c( 0, 20, 40, 60,   0,  15,  45,  80),
                   "LD" = c(10, 30, 50, 70,   5,  30,  60, 100),
                  "VAL" = c( 6,  4,  3, 10, 0.1, 0.9, 2.5,   6),
                   stringsAsFactors = FALSE)
m1 <- mpspline(obj = dat, var_name = 'VAL')

# multiple variables
dat_multi <- data.frame( "SID" = c( 1,  1,  1,  1,   2,   2,   2,   2),
                          "UD" = c( 0, 20, 40, 60,   0,  15,  45,  80),
                          "LD" = c(10, 30, 50, 70,   5,  30,  60, 100),
                        "VAL1" = c( 6,  4,  3, 10, 0.1, 0.9, 2.5,   6),
                        "VAL2" = c( 5,  3,  2,  9, 0.2, 1.0, 2.0,   5),
                        stringsAsFactors = FALSE)
m_multi <- mpspline(obj = dat_multi, var_name = c('VAL1', 'VAL2'))
# access results: m_multi[['VAL1']][['1']]