R: Covariance between two spectrograms

covspectro {seewave}

R Documentation

Covariance between two spectrograms

Description

This function tests the similarity between two spectrograms by returning their maximal covariance and the time shift related to it.

Usage

covspectro(wave1, wave2, f, channel = c(1,1), wl = 512, wn = "hanning", n,
plot = TRUE, plotval = TRUE,
method = "spearman", col = "black", colval = "red", cexval = 1,
fontval = 1, xlab = "Time (s)",
ylab = "Normalised covariance (cov)", type = "l", pb = FALSE, ...)

Arguments

`wave1`	a first R object.
`wave2`	a second R object.
`f`	sampling frequency of `wave` (in Hz). Does not need to be specified if embedded in `wave`.
`channel`	channel of the R objects, by default left channel (1) for each object.
`wl`	length of the window for the analysis (even number of points, by default = 512).
`wn`	window name, see `ftwindow` (by default `"hanning"`).
`n`	number of covariances computed between `wave1` and `wave2` when sliding `wave2` along `wave1`.
`plot`	logical, if `TRUE` plots r values against frequency shift (by default `TRUE`).
`plotval`	logical, if `TRUE` adds to the plot maximum R value and frequency offset (by default `TRUE`).
`method`	a character string indicating which correlation coefficient is to be computed ("pearson", "spearman", or "kendall") (see `cor`).
`col`	colour of r values.
`colval`	colour of r max and frequency offset values.
`cexval`	character size of r max and frequency offset values.
`fontval`	font of r max and frequency offset values.
`xlab`	title of the frequency axis.
`ylab`	title of the r axis.
`type`	if `plot` is `TRUE`, type of plot that should be drawn. See `plot` for details (by default "l" for lines).
`pb`	if `TRUE` returns a text progress bar in the console.
`...`	other `plot` graphical parameters.

Details

Successive covariances between the spectrogram of wave1 and the spectrogram of wave2 are computed when regularly sliding forward and backward wave2 along wave1.
The maximal covariance is obtained at a particular shift (time offset). This shift may be positive or negative.
n sets in how many steps wave2 will be slided along wave1. Time process can be then decreased by setting low n value.
Inverting wave1 and wave2 may give slight different results.

Value

If plot is FALSE, covspectro returns a list containing three components:

`cov`	the successive covariance values between `wave1` and `wave2`.
`covmax`	the maximum covariance between `wave1` and `wave2`.
`t`	the time offset corresponding to `cov`.

Author(s)

Jerome Sueur sueur@mnhn.fr

References

Hopp, S. L., Owren, M. J. and Evans, C. S. (Eds) 1998. Animal acoustic communication. Springer, Berlin, Heidelberg.

Examples

# covariance between two notes of a birdsong
## Not run: 
data(tico)
note1<-cutw(tico, f=22050, from=0.5, to=0.9)
note2<-cutw(tico, f=22050, from=0.9, to=1.3)
covspectro(note1,note2,f=22050,n=37)

## End(Not run)

[Package seewave version 2.1.6 Index]