seewave (version 1.7.0)

fbands: Frequency bands plot

Description

This graphical function returns a frequency spectrum as a bar plot.

Usage

fbands(spec, f = NULL, bands = 10, width = FALSE, plot = TRUE,
xlab = "Frequency (kHz)", ylab = "Relative amplitude", ...)

Value

• A two-column matrix, the first column corresponding to the frequency values (x-axis, mean of the bars limits) and the second column corresponding to height values (y-axis) of the bars.

Details

The function proceeds as follows

• divides the spectrum in bands. The limits of the bands are set with the argumentbands. There are two options:
  • you set a number of bands with equal size by giving a single value tobands. For instance, settingbandsto a value of 10 will slice the spectrum in 10 equal parts and return 10 local peaks.
  • you set the limits of the bands. This is achieve by giving a numeric vector tobands. The limits can follow a regular or irregular series. For instance attributing the vector c(0,2,4,8) will generate the following bands [0,2[, [2,4[, [4,8] kHz. Be aware that the last value should not exceed half the sampling frequency used to obtain the spectrumspec.
• uses the functionbarplot.

See Also

meanspec, spec, barplot.

Examples

data(sheep)
spec <- meanspec(sheep, f=8000, plot=FALSE)
# default plot
fbands(spec)
# setting a specific number of bands
fbands(spec, bands=6)
#setting specific regular bands limits
fbands(spec, bands=seq(0,4,by=0.25))
# some plot tuning
op <- par(las=1)
fbands(spec, bands=seq(0,4,by=0.1),
       horiz=TRUE, col=heat.colors(41),
       xlab="", ylab="",
       cex.axis=0.75, cex.names = 0.75,
       axes=FALSE)
par(op)
# showing or not the width of the bands
oct <- octaves(440,3)/1000
op <- par(mfrow=c(2,1))
fbands(spec, bands=oct, col="blue")
fbands(spec, bands=oct, width = TRUE, col="red")
par(op)
# kind of horizontal zoom
op <- par(mfrow=c(2,1))
fbands(spec, bands=seq(0,4,by=0.2), col=c(rep(1,10),
   rep("orange",5),rep(1,5)), main="all frequency range")
fbands(spec, bands=seq(2,3,by=0.2),
   col="orange", main="a subset or zoom in")
par(op)
# kind of dynamic frequency bands
specs <- dynspec(sheep, f=8000, plot= FALSE)$amp
out <- apply(specs, f=8000, MARGIN=2,
     FUN = fbands, bands = seq(0,4,by=0.2),
     col = 1, ylim=c(0,max(specs)))