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Rwave (version 1.2)

snake: Ridge Estimation by Snake Method

Description

Estimate a ridge from a time-frequency representation, using the snake method.

Usage

snake(tfrep, guessA, guessB, snakesize=length(guessB),
tfspec=numeric(dim(modulus)[2]), subrate=1, temprate=3, muA=1,
muB=muA, lambdaB=2 * muB, lambdaA=2 * muA, iteration=1000000,
seed=-7, costsub=1, stagnant=20000, plot=T)

Arguments

tfrep
Time-Frequency representation (real valued).
guessA
Initial guess for the algorithm (frequency variable).
guessB
Initial guess for the algorithm (time variable).
snakesize
the length of the initial guess of time variable.
tfspec
Estimate for the contribution of the noise to modulus.
subrate
Subsampling rate for ridge estimation.
temprate
Initial value of temperature parameter.
muA
Coefficient of the ridge's derivative in cost function (frequency component).
muB
Coefficient of the ridge's derivative in cost function (time component).
lambdaB
Coefficient of the ridge's second derivative in cost function (time component).
lambdaA
Coefficient of the ridge's second derivative in cost function (frequency component).
iteration
Maximal number of moves.
seed
Initialization of random number generator.
costsub
Subsampling of cost function in output.
stagnant
maximum number of steps without move (for the stopping criterion)
plot
when set (by default), certain results will be displayed

Value

  • Returns a structure containing:
  • ridge1D array (of same length as the signal) containing the ridge.
  • cost1D array containing the cost function.

References

See discussions in the text of ``Practical Time-Frequency Analysis''.

See Also

corona, coronoid, icm, snakoid.