| ptwgrid {ptw} | R Documentation |
Calculates values of the chosen optimization criterion (RMS or WCC) on a grid defined by the coefficients of the warping function.
ptwgrid(ref, samp, selected.traces,
coef.mins, coef.maxs, coef.lengths,
optim.crit = c("WCC", "RMS"),
smooth.param = 1e05,
trwdth = 20)
ref |
reference. Either a vector (containing one reference signal) or a matrix (one reference per row). If more than one reference is specified, the number of reference signals must equal the number of sample signals |
samp |
sample. A vector (containing one sample signal) or a matrix (one sample per row). If more than one sample is specified, the number of sample signals must equal the number of reference signals |
selected.traces |
optional vector containing the row numbers to
use from ref (if more than one reference signal is specified)
and samp |
coef.mins |
a vector containing the respective minimal values of coefficients for the grid. The first number is the minimal zeroth-order coefficient (i.e., a constant shift); further numbers indicate the minimal linear, quadratic, ... stretches |
coef.maxs |
a vector containing the maximal values of coefficients for the grid |
coef.lengths |
a vector of the same length as coef.maxs and coef.mins containing the number of steps in which to vary the respective coefficients between their minimum and maximum value |
optim.crit |
either "WCC" or "RMS". In both cases,
the optimal value of the alignment leads to a value of 0. For "WCC",
this means that 1 - WCC is optimized rather than WCC
(where the optimal value equals 1) |
smooth.param |
smoothing parameter for smoothing the reference
and sample when optim.crit equals "RMS". If no
smoothing is required, set this to 0 |
trwdth |
the width of the triangle in the WCC criterion during the optimization, given as a number of data points. Default: 20 |
In contrast to ptw, only the three situations leading to one warping function are distinguished here:
Which situation is applicable is determined from the dimensions of
ref and samp.
An array of dimension length(coef.mins) and maximal indices
per dimension specified by coef.lengths
Tom Bloemberg, Jan Gerretzen, Ron Wehrens
## Not run:
data(gaschrom)
mygrid <- ptwgrid(gaschrom[1,], gaschrom[16,],
coef.mins = c(-10, .9), coef.max = c(10, 1.1),
coef.lengths = c(21, 21))
image(seq(-10, 10, length = 21),
seq(.9, 1.1, length = 21),
mygrid)
## End(Not run)