R: Ridge Estimation by Snake Method

snake {Rwave} | R Documentation

## 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=TRUE)

### 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:

`ridge` | 1D array (of same length as the signal) containing the ridge.
`cost` | 1D array containing the cost function.

### References

See discussions in the text of “Practical Time-Frequency Analysis”.

### See Also

`corona`, `coronoid`, `icm`, `snakoid`.

[Package Rwave version 2.6-0 Index]