ks.dist {seewave}

Kolmogorov-Smirnov distance

Description

This function compares two distributions (e.g. two frequency spectra) by computing the Kolmogorov-Smirnov distance

Usage

ks.dist(spec1, spec2, f = NULL, mel = FALSE,
plot = FALSE, type = "l",
lty = c(1, 2), col = c(2, 4), 
flab = NULL, alab = "Cumulated amplitude",
flim = NULL, alim = NULL,
title = TRUE, legend = TRUE, ...)

Arguments

spec1

any distribution, especially a spectrum obtained with spec or meanspec (not in dB). This can be either a two-column matrix (col1 = frequency, col2 = amplitude) or a vector (amplitude).

spec2

any distribution, especially a spectrum obtained with spec or meanspec (not in dB). This can be either a two-column matrix (col1 = frequency, col2 = amplitude) or a vector (amplitude).

f

sampling frequency of waves used to obtain spec1 and spec2 (in Hz). Not necessary if spec1 and/or spec2 is a two columns matrix obtained with spec or meanspec.

mel

a logical, if TRUE the (htk-)mel scale is used.

plot

logical, if TRUE plots both cumulated spectra and their maximal distance (i.e. the K-S distance.)

type

if plot is TRUE, type of plot that should be drawn. See plot for details (by default "l" for lines).

lty

a vector of length 2 for the line type of spec1 and spec2 if type="l".

col

a vector of length 2 for the colour of spec1 and spec2.

flab

title of the frequency axis.

alab

title of the amplitude axis.

flim

the range of frequency values.

alim

range of amplitude axis.

title

logical, if TRUE, adds a title with D and F values.

legend

logical, if TRUE adds a legend to the plot.

...

other plot graphical parameters.

Details

The Kolmogorov distance is the maximal distance between the cumulated spectra. The function returns this distance and the corresponding frequency. This is an adaptation of the statistic computed by the non-parametric Kolmogorov-Smirnov test (see ks.test).

Value

The function returns a list of two items

D

the Kolomogorov-Smirnov distance

F

the frequency (in KHz) where the Kolmogorov-Smirnov distance was found

Note

There is no p-value associated to the K-S distance.
If no frequency is provided, only the distance D.

Author(s)

Jerome Sueur, improved by Laurent Lellouch

See Also

kl.dist, simspec, diffspec, logspec.dist, diffcumspec, itakura.dist

Examples

## Comparison of two spectra and plot of the cumulated spectra with the K-S distance
data(tico)
tico1 <- spec(tico, at=0.65, plot=FALSE)
tico2 <- spec(tico, at=1.1, plot=FALSE)
ks.dist(tico1, tico2, plot=TRUE)
## mel scale
require(tuneR)
data(orni)
orni.mel <- melfcc(orni, nbands = 256, dcttype = "t3", fbtype = "htkmel", spec_out=TRUE)
orni.mel.mean <- apply(orni.mel$aspectrum, MARGIN=2, FUN=mean)
tico.mel <- melfcc(tico, nbands = 256, dcttype = "t3", fbtype = "htkmel", spec_out=TRUE)
tico.mel.mean <- apply(tico.mel$aspectrum, MARGIN=2, FUN=mean)
ks.dist(orni.mel.mean, tico.mel.mean, f=22050, mel=TRUE, plot=TRUE)