R: Modified Snake Method

snakoid {Rwave} | R Documentation

## Modified Snake Method

### Description

Estimate a ridge from a time-frequency representation, using the modified snake method (modified cost function).

### Usage

    snakoid(modulus, 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

`modulus` | 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 first guess of time variable.
`tfspec` | Estimate for the contribution of srthe 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 stationary iterations before stopping.
`plot` | when set(default), some 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.
`plot` | when set(default), some results will be displayed.

### References

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

### See Also

`corona`, `coronoid`, `icm`, `snake`.

[Package Rwave version 2.4-8 Index]